docs: Phase 2 - Add Skeleton Loaders and Color Theme System sections

MAJOR FEATURES DOCUMENTED:

### Section 11: Skeleton Loaders (lines 1638-1764)
Component-level content placeholders for smooth loading transitions

KEY FEATURES:
- Pixel-perfect skeleton matching (header, photo, sections, experience)
- GPU-accelerated shimmer animation (1.8s ease-in-out infinite)
- Component-wrapper architecture (dual-state: actual + skeleton)
- HTMX event integration (beforeSwap → show, afterSettle → hide)
- Zero layout shift during transitions
- Accessibility: Respects prefers-reduced-motion
- Print-friendly: Skeletons hidden in @media print

IMPLEMENTATION:
- static/css/skeleton.css (341 lines)
- templates/partials/skeleton-loader.html
- HTMX event listeners in main.js
- tests/mjs/12-skeleton-language-transitions.test.mjs

BENEFITS:
- Professional UX like modern SPAs (LinkedIn, Facebook)
- Smooth 250ms fade transitions
- Reusable for any HTMX swap operation
- Independent component loading states

### Section 12: Color Theme System (lines 1767-1939)
Dynamic light/dark/auto theme switching with CSS custom properties

KEY FEATURES:
- Three theme modes: Auto (system), Light, Dark
- CSS custom properties for instant switching
- localStorage persistence across sessions
- System integration via prefers-color-scheme
- Dynamic button colors per theme mode:
  * Auto: Purple (#9b59b6)
  * Light: Orange/Yellow (#f39c12)
  * Dark: Blue (#3498db)
- Dual-theme architecture (Color + Layout independent)

IMPLEMENTATION:
- static/css/color-theme.css (258 lines)
- static/hyperscript/color-theme._hs (59 lines)
- setColorTheme(), initColorTheme() functions
- Fixed floating button with theme cycling
- tests/mjs/13-color-theme-switcher.test.mjs

BENEFITS:
- User comfort (choose preference or follow system)
- Instant switching (CSS custom properties, no reflow)
- Accessible (WCAG AA contrast compliance)
- Zero JavaScript for theme application
- Separation of concerns (color vs. layout)

DOCUMENTATION QUALITY:
- Complete before/after code examples
- Architecture pattern breakdowns
- Comprehensive benefits lists
- Testing information included
- Pixel-perfect matching tables (skeletons)
- CSS custom properties reference (theme)

IMPACT: +306 lines comprehensive documentation
TIME: ~90 minutes (partial Phase 2 complete)
REMAINING: HTMX patterns enhancement, hover sync documentation

doc/MODERN-WEB-TECHNIQUES.md

@@ -1635,6 +1635,310 @@ Time 600ms+: opacity=NaN                          ← Element destroyed!
 
 ---
 
+### 11. Skeleton Loaders - Component-Level Content Placeholders
+
+**Problem:** Language transitions caused jarring white screen flashes as new content loaded. Users experienced:
+- Abrupt blank states during HTMX swaps
+- No visual continuity during async operations
+- Unclear loading state
+- Layout shift after content loaded
+
+**Solution:** Component-level skeleton loaders with pixel-perfect placeholder matching.
+
+#### Before (Jarring Transitions):
+```html
+<!-- User clicks language toggle -->
+<!-- Screen goes blank while waiting for server -->
+<!-- Content suddenly appears -->
+<!-- User confused about what happened -->
+```
+
+#### After (Smooth Skeleton Transitions):
+```html
+<!-- Component wrapper with dual states -->
+<div class="component-wrapper" data-component="header">
+    <!-- Actual content (visible by default) -->
+    <div class="actual-content">
+        <h1>Juan Teodoro</h1>
+        <p>15+ Years Full-Stack Experience</p>
+    </div>
+
+    <!-- Skeleton content (hidden by default) -->
+    <div class="skeleton-content">
+        <div class="skeleton skeleton-name"></div>
+        <div class="skeleton skeleton-experience-years"></div>
+    </div>
+</div>
+```
+
+```css
+/* static/css/skeleton.css - Component-level skeleton system */
+
+/* Base skeleton with shimmer animation */
+.skeleton {
+  background: linear-gradient(90deg, #f0f0f0 0%, #e8e8e8 20%, #f0f0f0 40%, #f0f0f0 100%);
+  background-size: 200% 100%;
+  animation: skeleton-shimmer 1.8s ease-in-out infinite;
+  border-radius: 4px;
+  will-change: background-position;
+  transform: translateZ(0); /* GPU acceleration */
+}
+
+@keyframes skeleton-shimmer {
+  0%   { background-position: 200% 0; }
+  100% { background-position: -200% 0; }
+}
+
+/* Loading state toggle */
+.component-wrapper.loading .actual-content {
+  opacity: 0;
+  pointer-events: none;
+}
+
+.component-wrapper.loading .skeleton-content {
+  opacity: 1;
+  pointer-events: all;
+}
+```
+
+```javascript
+// Language switch with skeleton loading
+htmx.on('htmx:beforeSwap', function(evt) {
+    // Show skeletons BEFORE swap
+    document.querySelectorAll('.component-wrapper').forEach(wrapper => {
+        wrapper.classList.add('loading');
+    });
+});
+
+htmx.on('htmx:afterSettle', function(evt) {
+    // Hide skeletons AFTER content settles
+    document.querySelectorAll('.component-wrapper').forEach(wrapper => {
+        wrapper.classList.remove('loading');
+    });
+});
+```
+
+**Architecture Pattern:**
+1. **User clicks language toggle** → HTMX `beforeSwap` event fires
+2. **JavaScript adds `.loading` class** → Triggers CSS transition (actual-content opacity: 1 → 0, skeleton-content opacity: 0 → 1)
+3. **Skeleton appears** → Smooth 250ms fade-in with shimmer animation
+4. **HTMX fetches new language content** → Server renders and returns HTML
+5. **HTMX swaps content** → New actual-content replaces old
+6. **afterSettle event fires** → JavaScript removes `.loading` class
+7. **Skeleton fades out** → Smooth 250ms fade (skeleton opacity: 1 → 0, actual-content opacity: 0 → 1)
+8. **Result** → Smooth, professional loading experience with zero layout shift
+
+**Benefits:**
+- ✅ **Zero layout shift** - Skeletons match exact dimensions of actual content
+- ✅ **Professional UX** - Smooth transitions like modern SPAs (LinkedIn, Facebook)
+- ✅ **Performance** - GPU-accelerated animations, CSS containment optimization
+- ✅ **Accessibility** - Respects `prefers-reduced-motion`, animations pause for users who need it
+- ✅ **Print-friendly** - Skeletons hidden in print CSS
+- ✅ **Maintainability** - Component-level structure, easy to add/modify skeletons
+- ✅ **Reusable** - Works for any HTMX swap operation, not just language switch
+
+**Implementation Locations:**
+- **CSS:** `static/css/skeleton.css` (341 lines) - Complete skeleton system
+- **Template:** `templates/partials/skeleton-loader.html` - Skeleton placeholders
+- **Component wrappers:** Each CV section wrapped with `.component-wrapper`
+- **HTMX events:** `static/js/main.js` - beforeSwap/afterSettle listeners
+
+**Testing:** Automated tests in `tests/mjs/12-skeleton-language-transitions.test.mjs` verify:
+- Skeletons appear during language switch
+- Content replaced without full page reload
+- Skeletons removed after content loads
+- Zero layout shift during transition
+
+**Pixel-Perfect Matching:**
+
+| Component | Skeleton Dimensions | Actual Content Match |
+|-----------|---------------------|----------------------|
+| Header name | 40px height, 75% width | `<h1>` tag exact size |
+| Experience years | 24px height, 55% width | Subtitle exact size |
+| Profile photo | 150x200px, absolute positioned | Photo exact dimensions |
+| Section titles | 24px height + icon gap | Title + iconify-icon |
+| Experience items | 60px logo + flex content | Logo + text layout |
+| Skill badges | 32px height pills | Actual skill badge size |
+
+**Key Innovation:** Component-level architecture allows each CV section to independently show loading state without affecting rest of page. Skeletons are absolutely positioned overlays, so they don't disrupt document flow.
+
+---
+
+### 12. Color Theme System - Dynamic Light/Dark/Auto Switching
+
+**Problem:** Users have different preferences for light vs. dark interfaces, and forced single theme causes:
+- Eye strain for users in low-light environments (forced light theme)
+- Poor contrast for users in bright environments (forced dark theme)
+- Inability to match system preferences
+- No user control over visual comfort
+
+**Solution:** CSS custom properties with dynamic theme switching (auto/light/dark modes).
+
+#### Before (Single Theme Only):
+```css
+/* Hard-coded light theme only */
+body {
+  background: #ffffff;
+  color: #1a1a1a;
+}
+```
+
+#### After (Dynamic Theme System):
+```css
+/* static/css/color-theme.css - CSS Custom Properties */
+
+/* Light theme (default) */
+:root {
+  --page-bg: #b8bbbe;
+  --paper-bg: #ffffff;
+  --text-primary: #1a1a1a;
+  --text-secondary: #333333;
+  --action-bar-bg: #2b2b2b;
+  --shadow-lg: 2px 2px 9px rgba(0, 0, 0, 0.5);
+}
+
+/* Dark theme override */
+[data-color-theme="dark"] {
+  --page-bg: rgb(82, 86, 89);
+  --paper-bg: #1a1a1a;
+  --text-primary: #e0e0e0;
+  --text-secondary: #d0d0d0;
+  --action-bar-bg: #1a1a1a;
+  --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.6);
+}
+
+/* Auto theme - follows system preference */
+@media (prefers-color-scheme: dark) {
+  [data-color-theme="auto"] {
+    /* Same dark theme variables */
+    --page-bg: rgb(82, 86, 89);
+    --paper-bg: #1a1a1a;
+    /* ... */
+  }
+}
+
+/* Components use custom properties */
+.cv-paper {
+  background: var(--paper-bg);
+  color: var(--text-primary);
+  box-shadow: var(--shadow-lg);
+}
+```
+
+```hyperscript
+-- static/hyperscript/color-theme._hs
+
+def setColorTheme(mode)
+  -- Save preference to localStorage
+  call localStorage.setItem('color-theme-mode', mode)
+
+  -- Apply theme to document
+  call document.documentElement.setAttribute('data-color-theme', mode)
+
+  -- Update button icon based on mode
+  if mode is 'light' then
+    call document.querySelector('#themeIcon').setAttribute('icon', 'mdi:white-balance-sunny')
+  end
+  if mode is 'dark' then
+    call document.querySelector('#themeIcon').setAttribute('icon', 'mdi:moon-waning-crescent')
+  end
+  if mode is 'auto' then
+    call document.querySelector('#themeIcon').setAttribute('icon', 'mdi:theme-light-dark')
+  end
+end
+
+def initColorTheme()
+  -- Get saved preference or default to 'auto'
+  set savedTheme to localStorage['color-theme-mode'] or 'auto'
+  call setColorTheme(savedTheme)
+end
+```
+
+**Theme Switcher UI:**
+```html
+<!-- Fixed floating button -->
+<button class="color-theme-switcher"
+        data-theme-mode="auto"
+        _="on click
+             set currentMode to localStorage['color-theme-mode'] or 'auto'
+             if currentMode is 'auto' then call setColorTheme('light')
+             else if currentMode is 'light' then call setColorTheme('dark')
+             else call setColorTheme('auto')
+             end">
+    <iconify-icon id="themeIcon" icon="mdi:theme-light-dark"></iconify-icon>
+</button>
+```
+
+```css
+/* Dynamic button colors based on active theme */
+.color-theme-switcher:hover[data-theme-mode="light"] {
+  background: #f39c12 !important; /* Warm sun yellow */
+}
+
+.color-theme-switcher:hover[data-theme-mode="dark"] {
+  background: #3498db !important; /* Cool moon blue */
+}
+
+.color-theme-switcher:hover[data-theme-mode="auto"] {
+  background: #9b59b6 !important; /* Purple (mix of both) */
+}
+```
+
+**Theme Cycle Sequence:**
+1. **Auto** (default) - Follows system preference via `prefers-color-scheme`
+2. **Light** - Force light theme regardless of system
+3. **Dark** - Force dark theme regardless of system
+4. **Back to Auto** - Return to system preference
+
+**Architecture Pattern:**
+1. **Page loads** → `initColorTheme()` runs, reads localStorage
+2. **User clicks theme button** → Cycles to next mode (auto → light → dark → auto)
+3. **`setColorTheme(mode)` executes** → Updates `data-color-theme` attribute on `<html>`
+4. **CSS cascade triggers** → All `var(--custom-property)` values update instantly
+5. **localStorage saves preference** → Persists across page reloads
+6. **Button icon updates** → Visual feedback (sun/moon/auto icons)
+7. **Button hover color changes** → Dynamic based on active mode
+
+**Benefits:**
+- ✅ **User comfort** - Choose preferred theme or follow system
+- ✅ **Instant switching** - CSS custom properties update without reflow
+- ✅ **Persistent** - localStorage saves preference across sessions
+- ✅ **Accessible** - High contrast in both modes, WCAG AA compliant
+- ✅ **System integration** - Auto mode respects OS/browser settings
+- ✅ **Visual feedback** - Dynamic button colors indicate active mode
+- ✅ **Separation of concerns** - Color theme independent from layout theme (.theme-clean)
+- ✅ **Performance** - Zero JavaScript for theme application (CSS handles it)
+
+**Implementation Locations:**
+- **CSS:** `static/css/color-theme.css` - Theme variables and button styles
+- **Hyperscript:** `static/hyperscript/color-theme._hs` (59 lines) - Theme switching logic
+- **Button:** Fixed position floating button (left: 2rem, bottom: 14rem on desktop)
+- **Mobile:** Repositioned in bottom action bar (5-button layout)
+
+**Testing:** Automated tests in `tests/mjs/13-color-theme-switcher.test.mjs` verify:
+- Theme cycling works (auto → light → dark → auto)
+- localStorage persistence across reloads
+- Button colors change per theme mode
+- Icons update correctly
+- `data-color-theme` attribute applied
+
+**CSS Custom Properties Used:**
+
+| Variable | Light Theme | Dark Theme | Purpose |
+|----------|-------------|------------|---------|
+| `--page-bg` | #b8bbbe (gray) | rgb(82,86,89) (darker gray) | Page background |
+| `--paper-bg` | #ffffff (white) | #1a1a1a (near-black) | CV paper background |
+| `--text-primary` | #1a1a1a (black) | #e0e0e0 (light gray) | Main text color |
+| `--action-bar-bg` | #2b2b2b (dark gray) | #1a1a1a (darker) | Top bar background |
+| `--shadow-lg` | 2px 2px 9px rgba(0,0,0,0.5) | 0 4px 16px rgba(0,0,0,0.6) | Paper shadow |
+
+**Key Innovation:** Dual-theme system (Color + Layout) allows complete customization:
+- **Color theme** (this section): Light/Dark/Auto color palette
+- **Layout theme** (.theme-clean): Sidebar vs. clean layout structure
+- Both independent, can be combined (e.g., dark mode + clean layout)
+
+---
+
 ## 🐛 Phase 9: Zoom Control Bug Fixes (November 2025)
 
 ### Issue 1: X Button Not Working