feat: add debug page with tables and logs viewer (Step 1)

Backend:
- Add /debug/tables endpoint to dump SQLite tables
- Add /debug/logs endpoint to read scrap.log

Frontend:
- Add react-router-dom for navigation
- Create HomePage and DebugPage components
- Add navigation bar with Debug link
- Style debug page with Gruvbox theme
- Fix package.json dependencies versions

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

.gitignore

@@ -1,5 +1,8 @@
 .venv/
+__pycache__/
+*.pyc
 backend/data/
 backend/logs/
 frontend/node_modules/
+frontend/dist/
 .env