feat: make Product fully independent from MarketplaceProduct

- Add is_digital and product_type columns to Product model
- Remove is_digital/product_type properties that derived from MarketplaceProduct
- Update Create form with translation tabs, GTIN type, sale price, VAT rate, image
- Update Edit form to allow editing is_digital (remove disabled state)
- Add Availability field to Edit form
- Fix Detail page for directly created products (no marketplace source)
- Update vendor_product_service to handle new fields in create/update
- Add VendorProductCreate/Update schema fields for translations and is_digital
- Add unit tests for is_digital column and direct product creation
- Add integration tests for create/update API with new fields
- Create product-architecture.md documenting the independent copy pattern
- Add migration y3d4e5f6g7h8 for is_digital and product_type columns

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/v1/vendor/products.py

@@ -15,6 +15,7 @@ from app.api.deps import get_current_vendor_api
 from app.core.database import get_db
 from app.services.product_service import product_service
 from app.services.subscription_service import subscription_service
+from app.services.vendor_product_service import vendor_product_service
 from models.database.user import User
 from models.schema.product import (
     ProductCreate,
@@ -25,6 +26,10 @@ from models.schema.product import (
     ProductToggleResponse,
     ProductUpdate,
 )
+from models.schema.vendor_product import (
+    VendorDirectProductCreate,
+    VendorProductCreateResponse,
+)
 
 router = APIRouter(prefix="/products")
 logger = logging.getLogger(__name__)
@@ -106,6 +111,50 @@ def add_product_to_catalog(
     return ProductResponse.model_validate(product)
 
 
+@router.post("/create", response_model=VendorProductCreateResponse)
+def create_product_direct(
+    product_data: VendorDirectProductCreate,
+    current_user: User = Depends(get_current_vendor_api),
+    db: Session = Depends(get_db),
+):
+    """
+    Create a new product directly without marketplace product.
+
+    This creates a Product and ProductTranslation without requiring
+    an existing MarketplaceProduct.
+    """
+    # Check product limit before creating
+    subscription_service.check_product_limit(db, current_user.token_vendor_id)
+
+    # Build data dict with vendor_id from token
+    data = {
+        "vendor_id": current_user.token_vendor_id,
+        "title": product_data.title,
+        "brand": product_data.brand,
+        "vendor_sku": product_data.vendor_sku,
+        "gtin": product_data.gtin,
+        "price": product_data.price,
+        "currency": product_data.currency,
+        "availability": product_data.availability,
+        "is_active": product_data.is_active,
+        "is_featured": product_data.is_featured,
+        "description": product_data.description,
+    }
+
+    product = vendor_product_service.create_product(db=db, data=data)
+    db.commit()
+
+    logger.info(
+        f"Product {product.id} created by user {current_user.username} "
+        f"for vendor {current_user.token_vendor_code}"
+    )
+
+    return VendorProductCreateResponse(
+        id=product.id,
+        message="Product created successfully",
+    )
+
+
 @router.put("/{product_id}", response_model=ProductResponse)
 def update_product(
     product_id: int,