feat: multi-Oracle server support with runtime switching

Complete implementation of multi-server Oracle database support:

Backend:
- Multi-pool Oracle with lazy loading per server
- Email-to-server cache for automatic server discovery
- JWT tokens include server_id claim
- /auth/check-identity and /auth/check-email endpoints
- /auth/my-servers endpoint for listing user's accessible servers
- Server switch with password re-authentication

Frontend:
- New ServerSelector component for header dropdown
- Multi-step login flow (identity → server → password)
- Server switching from header with password modal
- Mobile drawer menu with server selection
- Dark mode support for all new components
- URL bookmark support with ?server= query param

Scripts:
- Unified start.sh replacing start-prod.sh/start-test.sh
- Unified ssh-tunnel.sh with multi-server support
- Updated status.sh for new architecture

Tests:
- E2E tests for multi-server and single-server login flows
- Backend unit tests for all new endpoints
- Oracle multi-pool integration tests

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

CLAUDE.md

@@ -35,17 +35,19 @@ See `docs/ARCHITECTURE-DECISIONS.md` for:
 
 ### Starting Services
 ```bash
-./start-prod.sh         # Backend :8000 + Frontend :3000 (PROD)
-./start-prod.sh stop    # Stop all services
-./ssh-tunnel-prod.sh    # Oracle DB tunnel (REQUIRED on Linux)
+./start.sh prod         # Backend :8000 + Frontend :3000 (PROD)
+./start.sh prod stop    # Stop all services
+./start.sh test         # Start in TEST mode
+./start.sh test stop    # Stop TEST services
+./ssh-tunnel.sh         # Oracle DB tunnel (for servers with SSH access)
 ./status.sh             # Check services
 ```
 
 ### Playwright Testing
 ```bash
 # Pentru testare UI cu Playwright:
-./start-test.sh         # Pornește în mod TEST
-./start-test.sh stop    # Oprește serverele
+./start.sh test         # Pornește în mod TEST
+./start.sh test stop    # Oprește serverele
 
 # Credențiale TEST:
 # User: MARIUS M