feat: add mobile gesture navigation system

Implemented comprehensive mobile gesture support for the Bible reader:

**Swipe Gestures:**
- Swipe left/right to navigate between chapters
- Only activates on mobile devices (touch events)
- Configurable 50px minimum swipe distance
- Prevents scrolling interference

**Tap Zones:**
- Left 25% of screen: navigate to previous chapter
- Right 25% of screen: navigate to next chapter
- Center 50%: normal reading interaction
- Maintains text selection capabilities

**Smooth Page Transitions:**
- Fade and scale animation on chapter navigation
- 300ms duration with ease-in-out timing
- Visual feedback: opacity 0.5 and scale 0.98 during transition
- Applied to all navigation methods (swipe, tap, keyboard, buttons)

**Settings Controls:**
- Enable/disable swipe gestures toggle
- Enable/disable tap zones toggle
- Pagination mode toggle (for future enhancement)
- All settings persist in localStorage

**Dependencies:**
- Added react-swipeable v7.0.2 for gesture handling
- Zero-dependency, lightweight (peer deps: React only)

**User Experience:**
- Settings grouped under "Mobile Navigation" section
- Default enabled for optimal mobile UX
- Touch-optimized for tablets and phones
- Desktop users can disable if desired

This completes all mobile navigation features from Phase 1.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

package.json

@@ -76,6 +76,7 @@
     "react": "^19.1.1",
     "react-dom": "^19.1.1",
     "react-markdown": "^10.1.0",
+    "react-swipeable": "^7.0.2",
     "recharts": "^3.2.1",
     "remark-gfm": "^4.0.1",
     "socket.io": "^4.8.1",