feat(backend): PDF deviz + portal client + SMS + invoice service

- PDF generation with WeasyPrint: deviz and factura templates (A4, branding)
- GET /orders/{id}/pdf/deviz returns PDF with order lines and totals
- Client portal (public, no auth): GET /p/{token}, POST /p/{token}/accept|reject
- SMS service (SMSAPI.ro) - skips in dev when no token configured
- Invoice service: create from validated order, auto-number (F-YYYY-NNNN)
- GET /invoices/{id}/pdf returns factura PDF
- Order status_client field for client accept/reject tracking
- Alembic migration for status_client
- 19 passing tests (auth + sync + orders + pdf + portal + invoices)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/main.py

@@ -4,9 +4,11 @@ from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
 from app.auth.router import router as auth_router
+from app.client_portal.router import router as portal_router
 from app.config import settings
 from app.db.base import Base
 from app.db.session import engine
+from app.invoices.router import router as invoices_router
 from app.orders.router import router as orders_router
 from app.sync.router import router as sync_router
 from app.vehicles.router import router as vehicles_router
@@ -34,6 +36,8 @@ app.include_router(auth_router, prefix="/api/auth")
 app.include_router(sync_router, prefix="/api/sync")
 app.include_router(orders_router, prefix="/api/orders")
 app.include_router(vehicles_router, prefix="/api/vehicles")
+app.include_router(invoices_router, prefix="/api/invoices")
+app.include_router(portal_router, prefix="/api")
 
 
 @app.get("/api/health")