feat(backend): sync endpoints + all models + seed + order workflow

- All business models: Vehicle, Order, OrderLine, Invoice, Appointment,
  CatalogMarca/Model/Ansamblu/Norma/Pret/TipDeviz/TipMotor, Mecanic
- Sync endpoints: GET /sync/full, GET /sync/changes?since=, POST /sync/push
  with tenant isolation and last-write-wins conflict resolution
- Order CRUD with state machine: DRAFT -> VALIDAT -> FACTURAT
  Auto-recalculates totals (manopera + materiale)
- Vehicle CRUD: list, create, get, update
- Seed data: 24 marci, 11 ansamble, 6 tipuri deviz, 5 tipuri motoare, 3 preturi
- Alembic migration for all business models
- 13 passing tests (auth + sync + orders)

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

backend/app/orders/router.py

@@ -0,0 +1,83 @@
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.db.session import get_db
+from app.deps import get_tenant_id
+from app.orders import schemas, service
+
+router = APIRouter()
+
+
+@router.get("")
+async def list_orders(
+    tenant_id: str = Depends(get_tenant_id),
+    db: AsyncSession = Depends(get_db),
+):
+    return await service.list_orders(db, tenant_id)
+
+
+@router.post("")
+async def create_order(
+    data: schemas.CreateOrderRequest,
+    tenant_id: str = Depends(get_tenant_id),
+    db: AsyncSession = Depends(get_db),
+):
+    order = await service.create_order(
+        db,
+        tenant_id,
+        data.vehicle_id,
+        data.tip_deviz_id,
+        data.km_intrare,
+        data.observatii,
+    )
+    return {"id": order.id}
+
+
+@router.get("/{order_id}")
+async def get_order(
+    order_id: str,
+    tenant_id: str = Depends(get_tenant_id),
+    db: AsyncSession = Depends(get_db),
+):
+    result = await service.get_order(db, tenant_id, order_id)
+    if not result:
+        raise HTTPException(status_code=404, detail="Order not found")
+    return result
+
+
+@router.post("/{order_id}/lines")
+async def add_line(
+    order_id: str,
+    data: schemas.AddLineRequest,
+    tenant_id: str = Depends(get_tenant_id),
+    db: AsyncSession = Depends(get_db),
+):
+    try:
+        line = await service.add_line(
+            db,
+            tenant_id,
+            order_id,
+            data.tip,
+            data.descriere,
+            data.ore,
+            data.pret_ora,
+            data.cantitate,
+            data.pret_unitar,
+            data.um,
+        )
+        return {"id": line.id}
+    except ValueError as e:
+        raise HTTPException(status_code=422, detail=str(e))
+
+
+@router.post("/{order_id}/validate")
+async def validate_order(
+    order_id: str,
+    tenant_id: str = Depends(get_tenant_id),
+    db: AsyncSession = Depends(get_db),
+):
+    try:
+        order = await service.validate_order(db, tenant_id, order_id)
+        return {"status": order.status}
+    except ValueError as e:
+        raise HTTPException(status_code=422, detail=str(e))