feat: refresh dashboard UX and backend integration

V4: AI-Driven Auto-Diff — Zero-effort Red/Green suggestions and 1-click 'Apply Fix' button

FEATURE: Dynamic Live-Diff — Code window now automatically updates to show Red/Green comparison of author fixes

V2: Full OpenEnv-Compliant Restructuring for Hackathon Submission

Final production readiness fixes: UI contrast, Groq support, dynamic headers, and removal of hardcoded elements.

Final Fix: Multi-mode deployment compliance (main(), entry points, uv.lock)

Initial Release v1.0 - Judge Ready