fix: correct tojson|safe usage in templates and update validator

- Remove |safe from |tojson in HTML attributes (x-data) - quotes must
  become " for browsers to parse correctly
- Update LANG-002 and LANG-003 architecture rules to document correct
  |tojson usage patterns:
  - HTML attributes: |tojson (no |safe)
  - Script blocks: |tojson|safe
- Fix validator to warn when |tojson|safe is used in x-data (breaks
  HTML attribute parsing)
- Improve code quality across services, APIs, and tests

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

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

models/schema/marketplace_product.py

@@ -73,7 +73,9 @@ class MarketplaceProductBase(BaseModel):
 
     # Categories
     google_product_category: str | None = None
-    product_type_raw: str | None = None  # Original feed value (renamed from product_type)
+    product_type_raw: str | None = (
+        None  # Original feed value (renamed from product_type)
+    )
     category_path: str | None = None
 
     # Custom labels
@@ -95,7 +97,9 @@ class MarketplaceProductBase(BaseModel):
     source_url: str | None = None
 
     # Product type classification
-    product_type_enum: str | None = None  # 'physical', 'digital', 'service', 'subscription'
+    product_type_enum: str | None = (
+        None  # 'physical', 'digital', 'service', 'subscription'
+    )
     is_digital: bool | None = None
 
     # Digital product fields
@@ -124,8 +128,6 @@ class MarketplaceProductUpdate(MarketplaceProductBase):
     All fields are optional - only provided fields will be updated.
     """
 
-    pass
-
 
 class MarketplaceProductResponse(BaseModel):
     """Schema for marketplace product API response."""