✨ feat(mobile): add BottomBar navigation and CheminLibre drawer (Story 3.7)

- Add ZoneCard component for zone display with status indicators
- Add CheminLibre drawer with vertical zone cards and path decoration
- Add BottomBar with Map, Progress, and Settings buttons
- Add ProgressDetail modal showing visited sections
- Add SettingsDrawer with language, consent, and reset options
- Add i18n translations for zone, cheminLibre, bottomBar, settings
- Add --bottom-bar-height CSS variable for spacing
- Modify layouts to include BottomBar on mobile (< 768px)
- Support safe-area-inset for iOS devices
- Touch targets minimum 48x48px for WCAG compliance

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/app/assets/css/main.css

@@ -3,3 +3,9 @@
 @tailwind base;
 @tailwind components;
 @tailwind utilities;
+
+@layer base {
+  :root {
+    --bottom-bar-height: 64px;
+  }
+}