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/integration/security/test_input_validation.py

@@ -4,6 +4,7 @@ Input validation tests for the API.
 
 Tests SQL injection prevention, parameter validation, and JSON validation.
 """
+
 import pytest
 
 
@@ -27,14 +28,10 @@ class TestInputValidation:
     def test_parameter_validation(self, client, admin_headers):
         """Test parameter validation for API endpoints"""
         # Test invalid pagination parameters
-        response = client.get(
-            "/api/v1/admin/products?limit=-1", headers=admin_headers
-        )
+        response = client.get("/api/v1/admin/products?limit=-1", headers=admin_headers)
         assert response.status_code == 422  # Validation error
 
-        response = client.get(
-            "/api/v1/admin/products?skip=-1", headers=admin_headers
-        )
+        response = client.get("/api/v1/admin/products?skip=-1", headers=admin_headers)
         assert response.status_code == 422  # Validation error
 
     def test_json_validation(self, client, admin_headers, test_company):
@@ -51,8 +48,6 @@ class TestInputValidation:
         response = client.post(
             "/api/v1/admin/vendors",
             headers=admin_headers,
-            json={
-                "name": "Test Vendor"
-            },  # Missing required company_id, vendor_code
+            json={"name": "Test Vendor"},  # Missing required company_id, vendor_code
         )
         assert response.status_code == 422  # Validation error