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/vendor/customers.py

@@ -90,7 +90,9 @@ def get_customer_orders(
     - Return order details
     """
     vendor = vendor_service.get_vendor_by_id(db, current_user.token_vendor_id)  # noqa: F841
-    return CustomerOrdersResponse(orders=[], message="Customer orders coming in Slice 5")
+    return CustomerOrdersResponse(
+        orders=[], message="Customer orders coming in Slice 5"
+    )
 
 
 @router.put("/{customer_id}", response_model=CustomerMessageResponse)