feat: add collapsible accordion for sidebars on mobile

PROBLEM:
- Left and right sidebars occupy too much space on mobile
- User wants curriculum (main content) prioritized on mobile
- Sidebars should be collapsed by default, expand only on user interaction

SOLUTION:
HTML Changes (cv-content.html):
- Wrapped each sidebar in accordion structure
- Added .sidebar-accordion-header with brain icon, title, and chevron
  * Left sidebar: "Technical Skills" / "Competencias Técnicas"
  * Right sidebar: "More Skills" / "Más Competencias"
- Added .sidebar-accordion-content wrapper around sidebar sections
- Added onclick="toggleSidebar(this)" handler

CSS Changes (main.css):
Desktop (default):
- .sidebar-accordion-header: display: none (hidden on desktop)
- .sidebar-accordion-content: always visible (no restrictions)

Mobile @ 900px:
- .sidebar-accordion-header: display: flex, styled as clickable bar
  * Padding: 1rem 1.5rem
  * Background: var(--sidebar-gray) with hover effects
  * Font: 700 weight, 1.1rem size
  * Chevron rotates 180deg when active
- .sidebar-accordion-content: collapsed by default
  * max-height: 0 (collapsed)
  * max-height: 5000px when .active (expanded)
  * Smooth transitions: 0.3s ease-out (close) / 0.5s ease-in (open)
  * Padding: 0 when closed, 1.5rem when open
- .cv-sidebar: padding: 0 (accordion header handles padding)

JavaScript Changes (index.html):
- Added toggleSidebar(header) function
  * Toggles .active class on header and content
  * Smooth expand/collapse animation via CSS max-height transition

DATA Changes (cv-en.json, cv-es.json):
- Updated summary with more professional, experience-focused description
- Emphasizes 18+ years experience, international clients, practical solutions

BEHAVIOR:
- Desktop: Sidebars always visible, no accordion headers
- Mobile: Sidebars collapsed by default showing only header bar
- Click header: Expands sidebar with smooth animation
- Click again: Collapses sidebar
- Main content prioritized and always visible
- Each sidebar toggles independently

static/css/main.css

@@ -569,6 +569,15 @@ iconify-icon {
     font-size: 0.9rem;
 }
 
+/* Sidebar Accordion - Hidden on desktop, visible on mobile */
+.sidebar-accordion-header {
+    display: none;
+}
+
+.sidebar-accordion-content {
+    /* Always visible on desktop */
+}
+
 .sidebar-section {
     margin-bottom: 2rem;
 }
@@ -1933,7 +1942,55 @@ a:focus {
         position: static !important;
         grid-column: unset;
         grid-row: unset;
-        padding: 2rem 1.5rem;
+        padding: 0 !important;
+    }
+
+    /* ========== Sidebar Accordion on Mobile ========== */
+    .sidebar-accordion-header {
+        display: flex !important;
+        align-items: center;
+        gap: 0.75rem;
+        padding: 1rem 1.5rem;
+        background: var(--sidebar-gray);
+        cursor: pointer;
+        user-select: none;
+        border-bottom: 2px solid rgba(0, 0, 0, 0.1);
+        transition: background-color 0.2s ease;
+    }
+
+    .sidebar-accordion-header:hover {
+        background: #c5c5c5;
+    }
+
+    .sidebar-accordion-header:active {
+        background: #b8b8b8;
+    }
+
+    .sidebar-accordion-header span {
+        font-weight: 700;
+        font-size: 1.1rem;
+        flex: 1;
+    }
+
+    .sidebar-accordion-header .chevron {
+        transition: transform 0.3s ease;
+    }
+
+    .sidebar-accordion-header.active .chevron {
+        transform: rotate(180deg);
+    }
+
+    .sidebar-accordion-content {
+        max-height: 0;
+        overflow: hidden;
+        transition: max-height 0.3s ease-out;
+        padding: 0 1.5rem;
+    }
+
+    .sidebar-accordion-content.active {
+        max-height: 5000px;
+        transition: max-height 0.5s ease-in;
+        padding: 1.5rem 1.5rem 0.5rem 1.5rem;
     }
 
     .page-1 .cv-main,