Implement Plyr-based video player with comprehensive YouTube UI blocking

Rewrote VideoPlayerWithChapters component using plyr-react with best practices:
- Use Plyr React component wrapper for proper integration
- Aggressive YouTube UI hiding with correct parameters (controls=0, disablekb=1, fs=0)
- Block right-click context menu globally
- Block developer tools shortcuts (F12, Ctrl+Shift+I/J, Ctrl+U)
- CSS pointer-events manipulation to block YouTube iframe interactions
- Only Plyr controls remain interactive
- Accurate time tracking via Plyr's timeupdate event
- Chapter jump functionality via Plyr's currentTime API
- Custom accent color support for Plyr controls
- Hide YouTube's native play button with ::after overlay

This implementation provides:
✅ Working timeline with accurate duration tracking
✅ Chapter navigation that jumps to correct timestamps
✅ Maximum prevention of YouTube UI access
✅ Custom Plyr controls with your accent color
✅ Right-click and dev tools blocking
✅ No "Watch on YouTube" or copy link buttons
✅ Clean user experience

Based on recommended plyr-react implementation patterns.

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

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

package.json

@@ -62,6 +62,7 @@
     "lowlight": "^3.3.0",
     "lucide-react": "^0.462.0",
     "next-themes": "^0.3.0",
+    "plyr": "^3.8.3",
     "plyr-react": "^6.0.0",
     "qrcode.react": "^4.2.0",
     "react": "^18.3.1",