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/services/test_stats_service.py

@@ -1,19 +1,19 @@
 # tests/unit/services/test_stats_service.py
 """Unit tests for StatsService following the application's testing patterns."""
+
 import uuid
+from unittest.mock import patch
 
 import pytest
 from sqlalchemy.exc import SQLAlchemyError
-from unittest.mock import patch, MagicMock
 
 from app.exceptions import AdminOperationException, VendorNotFoundException
 from app.services.stats_service import StatsService
 from models.database.inventory import Inventory
-from models.database.marketplace_import_job import MarketplaceImportJob
 from models.database.marketplace_product import MarketplaceProduct
-from models.database.marketplace_product_translation import MarketplaceProductTranslation
-from models.database.product import Product
-from models.database.vendor import Vendor
+from models.database.marketplace_product_translation import (
+    MarketplaceProductTranslation,
+)
 
 
 def create_marketplace_product_with_translation(
@@ -21,8 +21,7 @@ def create_marketplace_product_with_translation(
 ):
     """Helper to create a MarketplaceProduct with its translation."""
     product = MarketplaceProduct(
-        marketplace_product_id=marketplace_product_id,
-        **kwargs
+        marketplace_product_id=marketplace_product_id, **kwargs
     )
     db.add(product)
     db.flush()  # Get the product ID
@@ -275,7 +274,10 @@ class TestStatsService:
             with pytest.raises(AdminOperationException) as exc_info:
                 self.service.get_marketplace_breakdown_stats(db)
 
-            assert exc_info.value.details.get("operation") == "get_marketplace_breakdown_stats"
+            assert (
+                exc_info.value.details.get("operation")
+                == "get_marketplace_breakdown_stats"
+            )
 
     # ==================== get_vendor_stats Tests ====================
 
@@ -371,9 +373,7 @@ class TestStatsService:
         stats = self.service.get_vendor_statistics(db)
 
         if stats["total_vendors"] > 0:
-            expected_rate = (
-                stats["verified_vendors"] / stats["total_vendors"] * 100
-            )
+            expected_rate = stats["verified_vendors"] / stats["total_vendors"] * 100
             assert abs(stats["verification_rate"] - expected_rate) < 0.01
 
     def test_get_vendor_statistics_database_error(self, db):
@@ -438,9 +438,7 @@ class TestStatsService:
         stats = self.service.get_import_statistics(db)
 
         if stats["total_imports"] > 0:
-            expected_rate = (
-                stats["completed_imports"] / stats["total_imports"] * 100
-            )
+            expected_rate = stats["completed_imports"] / stats["total_imports"] * 100
             assert abs(stats["success_rate"] - expected_rate) < 0.01
         else:
             assert stats["success_rate"] == 0