Add tunnel scripts for eduroam dev, fix AI analyze endpoint errors

- Rewrite start_backend.bat/sh with localtunnel for backend tunneling on NAT networks
- Add tunnel.js (extracted from bat to avoid CMD escaping issues)
- Fix frontend AI analyze: surface actual error details instead of generic "Analysis failed"
- Fix field name mismatch: frontend reads generated_photo_urls instead of nonexistent photos
- Add debug logging to backend JWT auth (HS256 failure reason)
- Remove deleted tests and .env.example

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>