Add CRM order queue: live sync, view modal, receipt tabs, delete

Wires the CRM (exoCRM GetOrders) into the dashboard as a locally
persisted order queue instead of the previous static mockup:

- CrmClient Protocol + ExoCrmClient/StubCrmClient for the CRM's
  signed JSON-RPC API
- Order model + migration, synced from CRM on each queue view;
  soft-deleted orders stay hidden across re-syncs
- GET/DELETE /api/v1/orders with "no receipt"/"receipt issued" tabs
  (the latter is empty until Checkbox fiscalization lands)
- Dashboard: real order list, item-detail modal, tab switcher,
  one-click delete

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/app/api/deps.py

@@ -10,9 +10,12 @@ from fastapi import Depends, HTTPException, status
 from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.core.config import settings
 from app.core.security import TokenError, decode_access_token
 from app.db.models.user import User, UserRole
 from app.db.session import get_session
+from app.services.crm.client import CrmClient
+from app.services.crm.exo_client import ExoCrmClient
 
 bearer_scheme = HTTPBearer(auto_error=False)
 
@@ -85,3 +88,10 @@ require_any = require_roles(UserRole.ADMIN, UserRole.CASHIER, UserRole.VIEWER)
 
 AdminUser = Annotated[User, Depends(require_admin)]
 CashierUser = Annotated[User, Depends(require_cashier)]
+
+
+def get_crm_client() -> CrmClient:
+    return ExoCrmClient(settings)
+
+
+CrmClientDep = Annotated[CrmClient, Depends(get_crm_client)]