feat(a11y): accessibility audit, high contrast, i18n foundation, skip nav (M17.1-M17.8)

- Keyboard navigation: useFocusTrap() for modals, useRovingTabindex() for grids
- ARIA audit: composables for focus trap and roving tabindex patterns
- High contrast mode: @media (prefers-contrast: more) + .high-contrast class
- i18n foundation: en/es/fr locale files, useI18n() composable with auto-detect
- RTL layout support: dir attribute toggling based on locale
- Dyslexia-friendly font: .font-dyslexia CSS class with OpenDyslexic support
- Skip navigation link: .skip-nav CSS with focus-visible positioning

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/app/src/styles/main.css

@@ -842,6 +842,60 @@ input:focus-visible {
   }
 }
 
+/* ===== HIGH CONTRAST MODE ===== */
+
+@media (prefers-contrast: more) {
+  .glass,
+  .glass-strong,
+  .glass-card {
+    border-color: rgba(255, 255, 255, 0.5);
+    backdrop-filter: none;
+    -webkit-backdrop-filter: none;
+  }
+
+  .text-white\/90,
+  .text-white\/80,
+  .text-white\/70 {
+    color: white !important;
+  }
+}
+
+.high-contrast .glass,
+.high-contrast .glass-strong,
+.high-contrast .glass-card {
+  border-color: rgba(255, 255, 255, 0.5);
+  backdrop-filter: none;
+  -webkit-backdrop-filter: none;
+}
+
+/* ===== SKIP NAVIGATION ===== */
+
+.skip-nav {
+  position: absolute;
+  top: -100%;
+  left: 0;
+  z-index: 9999;
+  padding: 8px 16px;
+  background: #F7931A;
+  color: #000;
+  font-weight: bold;
+  font-size: 14px;
+  text-decoration: none;
+  border-radius: 0 0 8px 0;
+}
+
+.skip-nav:focus {
+  top: 0;
+}
+
+/* ===== DYSLEXIA FONT ===== */
+
+.font-dyslexia {
+  font-family: 'OpenDyslexic', sans-serif;
+  letter-spacing: 0.05em;
+  line-height: 1.6;
+}
+
 /* ===== REDUCED MOTION ===== */
 
 @media (prefers-reduced-motion: reduce) {