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>

backend/modules/data_entry/routers/nomenclature.py

@@ -1,7 +1,7 @@
 """Nomenclature API endpoints."""
 
 from typing import Optional, List, Annotated
-from fastapi import APIRouter, Depends, HTTPException, Header
+from fastapi import APIRouter, Depends, HTTPException, Header, Request
 from sqlalchemy.ext.asyncio import AsyncSession
 from pydantic import BaseModel
 
@@ -190,14 +190,16 @@ async def get_cash_registers(
 
 @router.post("/sync/suppliers", response_model=SyncResult)
 async def sync_suppliers(
+    request: Request,
     company_id: Optional[int] = None,
     session: AsyncSession = Depends(get_session),
     selected_company: SelectedCompany = None,
 ):
     """Manually trigger supplier sync from Oracle."""
     cid = company_id or selected_company
+    server_id = getattr(request.state, 'server_id', None)
 
-    synced, errors = await SyncService.sync_suppliers(session, cid)
+    synced, errors = await SyncService.sync_suppliers(session, cid, server_id=server_id)
 
     return SyncResult(
         synced=synced,
@@ -208,14 +210,16 @@ async def sync_suppliers(
 
 @router.post("/sync/cash-registers", response_model=SyncResult)
 async def sync_cash_registers(
+    request: Request,
     company_id: Optional[int] = None,
     session: AsyncSession = Depends(get_session),
     selected_company: SelectedCompany = None,
 ):
     """Manually trigger cash register sync from Oracle."""
     cid = company_id or selected_company
+    server_id = getattr(request.state, 'server_id', None)
 
-    synced, errors = await SyncService.sync_cash_registers(session, cid)
+    synced, errors = await SyncService.sync_cash_registers(session, cid, server_id=server_id)
 
     return SyncResult(
         synced=synced,
@@ -226,18 +230,20 @@ async def sync_cash_registers(
 
 @router.post("/sync/all", response_model=dict)
 async def sync_all_nomenclatures(
+    request: Request,
     company_id: Optional[int] = None,
     session: AsyncSession = Depends(get_session),
     selected_company: SelectedCompany = None,
 ):
     """Sync all nomenclatures (suppliers + cash registers) from Oracle."""
     cid = company_id or selected_company
+    server_id = getattr(request.state, 'server_id', None)
 
     # Sync suppliers
-    suppliers_synced, suppliers_errors = await SyncService.sync_suppliers(session, cid)
+    suppliers_synced, suppliers_errors = await SyncService.sync_suppliers(session, cid, server_id=server_id)
 
     # Sync cash registers
-    registers_synced, registers_errors = await SyncService.sync_cash_registers(session, cid)
+    registers_synced, registers_errors = await SyncService.sync_cash_registers(session, cid, server_id=server_id)
 
     return {
         "suppliers": {