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/services/vendor_product_service.py

@@ -47,6 +47,7 @@ class VendorProductService:
             .options(
                 joinedload(Product.vendor),
                 joinedload(Product.marketplace_product),
+                joinedload(Product.translations),
             )
         )
 
@@ -246,26 +247,67 @@ class VendorProductService:
 
         Args:
             db: Database session
-            data: Product data dict
+            data: Product data dict (includes translations dict for multiple languages)
 
         Returns:
             Created Product instance
         """
+        from models.database.product_translation import ProductTranslation
+
+        # Determine product_type from is_digital flag
+        is_digital = data.get("is_digital", False)
+        product_type = "digital" if is_digital else data.get("product_type", "physical")
+
         product = Product(
             vendor_id=data["vendor_id"],
             vendor_sku=data.get("vendor_sku"),
             brand=data.get("brand"),
             gtin=data.get("gtin"),
-            price=data.get("price"),
+            gtin_type=data.get("gtin_type"),
             currency=data.get("currency", "EUR"),
+            tax_rate_percent=data.get("tax_rate_percent", 17),
             availability=data.get("availability"),
+            primary_image_url=data.get("primary_image_url"),
             is_active=data.get("is_active", True),
             is_featured=data.get("is_featured", False),
-            is_digital=data.get("is_digital", False),
-            description=data.get("description"),
+            is_digital=is_digital,
+            product_type=product_type,
         )
 
+        # Handle price fields via setters (convert to cents)
+        if data.get("price") is not None:
+            product.price = data["price"]
+        if data.get("sale_price") is not None:
+            product.sale_price = data["sale_price"]
+
         db.add(product)
+        db.flush()  # Get the product ID
+
+        # Handle translations dict (new format with multiple languages)
+        translations = data.get("translations")
+        if translations:
+            for lang, trans_data in translations.items():
+                if trans_data and (trans_data.get("title") or trans_data.get("description")):
+                    translation = ProductTranslation(
+                        product_id=product.id,
+                        language=lang,
+                        title=trans_data.get("title"),
+                        description=trans_data.get("description"),
+                    )
+                    db.add(translation)
+        else:
+            # Fallback for old format with single title/description
+            title = data.get("title")
+            description = data.get("description")
+            if title or description:
+                translation = ProductTranslation(
+                    product_id=product.id,
+                    language="en",
+                    title=title,
+                    description=description,
+                )
+                db.add(translation)
+
         db.flush()
 
         logger.info(f"Created vendor product {product.id} for vendor {data['vendor_id']}")
@@ -327,7 +369,6 @@ class VendorProductService:
             product.cost = data["cost"]  # Uses property setter
 
         # Update other allowed fields
-        # Note: is_digital is derived from marketplace_product, not directly updatable
         updatable_fields = [
             "vendor_sku",
             "brand",
@@ -335,6 +376,8 @@ class VendorProductService:
             "gtin_type",
             "currency",
             "tax_rate_percent",
+            "availability",
+            "is_digital",
             "is_active",
             "is_featured",
             "primary_image_url",
@@ -370,9 +413,22 @@ class VendorProductService:
         """Build a product list item dict."""
         mp = product.marketplace_product
 
-        # Get title from marketplace product translations
+        # Get title: prefer vendor translations, fallback to marketplace translations
         title = None
-        if mp:
+        # First try vendor's own translations
+        if product.translations:
+            for trans in product.translations:
+                if trans.language == language and trans.title:
+                    title = trans.title
+                    break
+            # Fallback to English if requested language not found
+            if not title:
+                for trans in product.translations:
+                    if trans.language == "en" and trans.title:
+                        title = trans.title
+                        break
+        # Fallback to marketplace translations
+        if not title and mp:
             title = mp.get_title(language)
 
         return {