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/database/marketplace_import_job.py

@@ -33,7 +33,9 @@ class MarketplaceImportError(Base, TimestampMixin):
     identifier = Column(String)  # marketplace_product_id, gtin, mpn, etc.
 
     # Error details
-    error_type = Column(String(50), nullable=False)  # missing_title, missing_id, parse_error, etc.
+    error_type = Column(
+        String(50), nullable=False
+    )  # missing_title, missing_id, parse_error, etc.
     error_message = Column(Text, nullable=False)
 
     # Raw row data for review (JSON)
@@ -64,7 +66,9 @@ class MarketplaceImportJob(Base, TimestampMixin):
     # Import configuration
     marketplace = Column(String, nullable=False, index=True, default="Letzshop")
     source_url = Column(String, nullable=False)
-    language = Column(String(5), nullable=False, default="en")  # Language for translations
+    language = Column(
+        String(5), nullable=False, default="en"
+    )  # Language for translations
 
     # Status tracking
     status = Column(