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/rules/claude-learn-deployment.md

@@ -23,8 +23,8 @@ Configure IIS web.config to proxy different API paths to different backend ports
 ## P: Scripturi pentru pornire/oprire servere ROA2WEB
 @2026-01-07 #scripts #server-management | explicit:high
 Serverele se pornesc și opresc DOAR cu scripturile dedicate:
-- `./start-prod.sh` - pornește tot (SSH tunnel + backend + frontend) în mod producție
-- `./start-test.sh` - pornește în mod test
+- `./start.sh prod` - pornește tot (SSH tunnel + backend + frontend) în mod producție
+- `./start.sh test` - pornește în mod test
 - `./start-backend.sh restart` - restartează doar backend-ul
 - `./start-frontend.sh restart` - restartează doar frontend-ul
 - `./status.sh` - verifică starea serviciilor