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>

tests/unit/models/database/test_team.py

@@ -1,5 +1,6 @@
 # tests/unit/models/database/test_team.py
 """Unit tests for VendorUser and Role database models."""
+
 import pytest
 
 from models.database.vendor import Role, Vendor, VendorUser
@@ -87,7 +88,9 @@ class TestVendorUserModel:
         assert vendor_user.role.name == "Manager"
         assert "products.create" in vendor_user.role.permissions
 
-    def test_vendor_user_multiple_vendors(self, db, test_vendor, test_user, other_company):
+    def test_vendor_user_multiple_vendors(
+        self, db, test_vendor, test_user, other_company
+    ):
         """Test same user can be added to multiple vendors."""
         # Create another vendor
         other_vendor = Vendor(