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>

tests/ocr-validation/README.md

@@ -13,9 +13,9 @@ Teste pentru validarea acurateții extragerii OCR din bonuri fiscale.
 ```bash
 # Pornește backend-ul
 cd /workspace/roa2web
-./start-prod.sh
+./start.sh prod
 # sau
-./start-test.sh
+./start.sh test
 ```
 
 ---
@@ -137,7 +137,7 @@ python tests/ocr-validation/get_raw_ocr_text.py tests/fixtures/ocr-samples/benzi
 ## Troubleshooting
 
 ### "Connection refused" sau "Failed to connect"
-- Backend-ul nu rulează. Pornește cu `./start-prod.sh`
+- Backend-ul nu rulează. Pornește cu `./start.sh prod`
 
 ### "401 Unauthorized"
 - JWT token invalid. Verifică `JWT_SECRET_KEY` în `.env`