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>

docs/data-entry/DATA-ENTRY-MODULE.md

@@ -398,12 +398,11 @@ Response: { total, by_status: { DRAFT: N, ... } }
 
 **Solution:**
 ```bash
-# Check which tunnel is running
-./ssh-tunnel-prod.sh status
-./ssh-tunnel-test.sh status
+# Check SSH tunnel status (for servers requiring SSH)
+./ssh-tunnel.sh status
 
-# Restart with correct tunnel
-./start-prod.sh  # or ./start-test.sh
+# Restart with correct environment
+./start.sh prod  # or ./start.sh test (test uses direct connection)
 ```
 
 ### 2. SQLite locked errors
@@ -420,7 +419,7 @@ Response: { total, by_status: { DRAFT: N, ... } }
 ps aux | grep uvicorn
 
 # Kill duplicates, restart
-./start-prod.sh restart
+./start.sh prod restart
 ```
 
 ### 3. Upload fails
@@ -497,9 +496,9 @@ npm run test
 
 ```bash
 # Start unified monolith (backend + frontend)
-./start-prod.sh  # Production Oracle server
+./start.sh prod  # Production Oracle server
 # OR
-./start-test.sh  # Test Oracle server
+./start.sh test  # Test Oracle server
 ```
 
 ### 2. Make Changes