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>

app/api/v1/admin/code_quality.py

@@ -329,9 +329,7 @@ async def assign_violation(
         "user_id": assignment.user_id,
         "assigned_at": assignment.assigned_at.isoformat(),
         "assigned_by": assignment.assigned_by,
-        "due_date": (
-            assignment.due_date.isoformat() if assignment.due_date else None
-        ),
+        "due_date": (assignment.due_date.isoformat() if assignment.due_date else None),
         "priority": assignment.priority,
     }