- Add Sessions tab to navigation between Dashboard and Projects
- Show active session count badge in navigation
- Create SessionsPage with:
- Last session section with resume button
- Active sessions grid with open/stop actions
- Recent sessions list
- Create session form with project/repo/tool selectors
- Add last_session_id to user config
- Update UserConfig schemas (backend and frontend)
- Add comprehensive CSS for sessions page
Quality gates: typecheck ✓, lint ✓, build ✓
Fusion