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/product_translation.py

@@ -154,7 +154,9 @@ class ProductTranslation(Base, TimestampMixin):
             # Description
             "description": self.get_effective_description(),
             "description_overridden": self.description is not None,
-            "description_source": mp_translation.description if mp_translation else None,
+            "description_source": mp_translation.description
+            if mp_translation
+            else None,
             # Short Description
             "short_description": self.get_effective_short_description(),
             "short_description_overridden": self.short_description is not None,