feat(website): add comprehensive accessibility improvements

Phase 1 - Screen Reader Critical:
- Add aria-label to main navigation
- Add accessible names to icon-only buttons (GitHub, theme toggle, close)
- Add aria-hidden to decorative SVGs and emoji icons
- Add role=dialog, aria-modal, aria-labelledby to modal
- Add skip link with visible focus state

Phase 2 - Keyboard Navigation:
- Implement focus trap in modal (Tab/Shift+Tab cycles)
- Return focus to trigger element on modal close
- Replace outline:none with visible focus rings
- Add keyboard navigation to install dropdown (arrows, escape)
- Add aria-expanded to dropdown toggles

Phase 3 - Dynamic Content:
- Add aria-live=polite to results counts and loading states
- Add role=listbox to search results
- Add role=list to resource lists
- Add role=menu/menuitem to dropdown menus

Phase 4 - Forms & Labels:
- Add .sr-only utility class for screen reader text
- Add visually hidden labels to all search inputs
- Add aria-label to filter dropdowns

Files modified:
- BaseLayout.astro, Modal.astro (ARIA attributes)
- modal.ts (focus trap, keyboard navigation)
- global.css (sr-only, skip-link, focus styles)
- All page files (labels, live regions, roles)

website/public/data/manifest.json

@@ -1,5 +1,5 @@
 {
-  "generated": "2026-02-01T23:32:16.397Z",
+  "generated": "2026-02-01T23:35:23.497Z",
   "counts": {
     "agents": 140,
     "prompts": 134,

website/public/styles/global.css

@@ -110,6 +110,39 @@ body {
   min-height: 100vh;
 }
 
+/* Accessibility Utilities */
+.sr-only {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px;
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  white-space: nowrap;
+  border: 0;
+}
+
+.skip-link {
+  position: absolute;
+  top: -100%;
+  left: 50%;
+  transform: translateX(-50%);
+  background: var(--color-accent);
+  color: var(--color-text-emphasis);
+  padding: 12px 24px;
+  border-radius: var(--border-radius);
+  font-weight: 600;
+  z-index: 10000;
+  transition: top var(--transition);
+}
+
+.skip-link:focus {
+  top: 12px;
+  outline: 2px solid var(--color-text-emphasis);
+  outline-offset: 2px;
+}
+
 .container {
   max-width: var(--container-width);
   margin: 0 auto;
@@ -348,7 +381,8 @@ a:hover {
 }
 
 .hero-search input:focus {
-  outline: none;
+  outline: 2px solid var(--color-accent);
+  outline-offset: 2px;
   border-color: var(--color-accent);
   box-shadow: var(--shadow-glow);
 }
@@ -651,6 +685,20 @@ a:hover {
   text-decoration: none;
 }
 
+.btn:focus {
+  outline: 2px solid var(--color-accent);
+  outline-offset: 2px;
+}
+
+.btn:focus:not(:focus-visible) {
+  outline: none;
+}
+
+.btn:focus-visible {
+  outline: 2px solid var(--color-accent);
+  outline-offset: 2px;
+}
+
 .btn-primary {
   background: var(--gradient-primary);
   color: white;
@@ -1024,7 +1072,8 @@ a:hover {
 }
 
 .search-bar input:focus {
-  outline: none;
+  outline: 2px solid var(--color-accent);
+  outline-offset: 2px;
   border-color: var(--color-accent);
   box-shadow: var(--shadow-glow);
 }
@@ -1068,7 +1117,8 @@ a:hover {
 }
 
 .filter-group select:focus {
-  outline: none;
+  outline: 2px solid var(--color-accent);
+  outline-offset: 2px;
   border-color: var(--color-accent);
 }