feat: enhance experience section with icons, duration, and improved styling

Experience Section Improvements:
- Increased company logo size from 48px to 64px
- Added default office building icon for companies without logos
- Increased spacing between entries (2.5rem margin, 2rem padding)
- Added visible separator lines (2px solid #ddd)
- Made dates bold (weight: 600) and larger (1.05rem)
- Changed date color to #555 for better contrast

Dynamic Duration Calculation:
- Added automatic years/months calculation for each position
- Format: "(4 years 10 months)", "(2 years)", "(6 months)"
- Smart pluralization in English and Spanish
- Handles current positions (calculates to today)
- Added Duration field to Experience model

Iconify Integration:
- Added Iconify library (v3.1.1) for icon management
- Replaced EN/ES text with round flag icons (circle-flags:us, circle-flags:es)
- Updated CV site icon to mdi:file-account
- Replaced toggle text with intuitive icons:
  * Short/Long: mdi:file-document-outline / mdi:file-document-multiple-outline
  * Logos: mdi:image-off-outline / mdi:image-multiple-outline
- Default company icon: mdi:office-building (64x64px, light gray background)

Logo Display:
- Logos now show by default (toggle checked on page load)
- Toggle controls icon visibility
- Consistent spacing with default icon placeholder

Files modified:
- internal/handlers/cv.go: Added calculateDuration() function
- internal/models/cv.go: Added Duration field to Experience struct
- templates/index.html: Iconify integration, flag icons, toggle icons
- templates/cv-content.html: Duration display, default icon logic
- static/css/main.css: Bold dates, larger font sizes
- static/css/logo-toggle.css: Icon styling, separator lines, spacing

static/css/logo-toggle.css

@@ -63,52 +63,103 @@
     font-size: 0.8rem;
     font-weight: 500;
     color: #999;
-    transition: color 0.3s ease;
+    transition: all 0.3s ease;
     white-space: nowrap;
+    display: flex;
+    align-items: center;
 }
 
-/* Highlight active label based on parent container state */
+/* Flag icons - special styling */
+.flag-icon {
+    border-radius: 50%;
+    overflow: hidden;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+}
+
+/* Highlight active label/icon based on parent container state */
 .language-toggle:has(#langToggle:not(:checked)) .toggle-label-left,
 .cv-length-toggle:has(#lengthToggle:not(:checked)) .toggle-label-left,
 .logo-toggle:has(#logoToggle:not(:checked)) .toggle-label-left {
     color: #fff;
+    opacity: 1;
 }
 
 .language-toggle:has(#langToggle:checked) .toggle-label-right,
 .cv-length-toggle:has(#lengthToggle:checked) .toggle-label-right,
 .logo-toggle:has(#logoToggle:checked) .toggle-label-right {
     color: #fff;
+    opacity: 1;
+}
+
+/* Dim inactive icons */
+.language-toggle:has(#langToggle:not(:checked)) .toggle-label-right,
+.cv-length-toggle:has(#lengthToggle:not(:checked)) .toggle-label-right,
+.logo-toggle:has(#logoToggle:not(:checked)) .toggle-label-right {
+    opacity: 0.4;
+}
+
+.language-toggle:has(#langToggle:checked) .toggle-label-left,
+.cv-length-toggle:has(#lengthToggle:checked) .toggle-label-left,
+.logo-toggle:has(#logoToggle:checked) .toggle-label-left {
+    opacity: 0.4;
 }
 
 /* Experience Item with Logo Support */
 .experience-item {
-    margin-bottom: 1.5rem;
+    margin-bottom: 2.5rem;
+    padding-bottom: 2rem;
+    border-bottom: 2px solid #ddd;
     page-break-inside: avoid;
     display: flex;
-    gap: 1rem;
+    gap: 1.2rem;
     position: relative;
 }
 
+.experience-item:last-child {
+    border-bottom: none;
+    padding-bottom: 0;
+}
+
 .company-logo {
-    display: none; /* Hidden by default */
+    display: block;
     flex-shrink: 0;
 }
 
 .company-logo img {
-    width: 48px;
-    height: 48px;
+    width: 64px;
+    height: 64px;
     object-fit: contain;
     border-radius: 4px;
     border: 1px solid #ddd;
     background: white;
 }
 
+.default-company-icon {
+    width: 64px;
+    height: 64px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border-radius: 4px;
+    border: 1px solid #ddd;
+    background: #f5f5f5;
+    color: #999;
+    padding: 8px;
+}
+
 .experience-content {
     flex: 1;
     min-width: 0; /* Prevents flex item from overflowing */
 }
 
-/* Show logos when toggle is active */
+/* Hide logos when toggle is OFF */
+.cv-paper:not(.show-logos) .company-logo {
+    display: none;
+}
+
+/* Show logos when toggle is ON (default) */
 .show-logos .company-logo {
     display: block;
 }

static/css/main.css

@@ -437,11 +437,16 @@ a:hover {
 
 .experience-period,
 .experience-separator,
-.experience-location {
-    color: #aaa;
-    font-weight: 500;
+.experience-location,
+.experience-duration {
+    color: #555;
+    font-weight: 600;
     display: inline-block;
-    font-size: 0.9rem;
+    font-size: 1.05rem;
+}
+
+.experience-duration {
+    font-style: italic;
 }
 
 .short-desc {