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/services/background_tasks_service.py

@@ -48,7 +48,9 @@ class BackgroundTasksService:
 
     def get_import_stats(self, db: Session) -> dict:
         """Get import job statistics"""
-        today_start = datetime.now(UTC).replace(hour=0, minute=0, second=0, microsecond=0)
+        today_start = datetime.now(UTC).replace(
+            hour=0, minute=0, second=0, microsecond=0
+        )
 
         stats = db.query(
             func.count(MarketplaceImportJob.id).label("total"),
@@ -57,7 +59,12 @@ class BackgroundTasksService:
             ).label("running"),
             func.sum(
                 func.case(
-                    (MarketplaceImportJob.status.in_(["completed", "completed_with_errors"]), 1),
+                    (
+                        MarketplaceImportJob.status.in_(
+                            ["completed", "completed_with_errors"]
+                        ),
+                        1,
+                    ),
                     else_=0,
                 )
             ).label("completed"),
@@ -83,12 +90,18 @@ class BackgroundTasksService:
 
     def get_test_run_stats(self, db: Session) -> dict:
         """Get test run statistics"""
-        today_start = datetime.now(UTC).replace(hour=0, minute=0, second=0, microsecond=0)
+        today_start = datetime.now(UTC).replace(
+            hour=0, minute=0, second=0, microsecond=0
+        )
 
         stats = db.query(
             func.count(TestRun.id).label("total"),
-            func.sum(func.case((TestRun.status == "running", 1), else_=0)).label("running"),
-            func.sum(func.case((TestRun.status == "passed", 1), else_=0)).label("completed"),
+            func.sum(func.case((TestRun.status == "running", 1), else_=0)).label(
+                "running"
+            ),
+            func.sum(func.case((TestRun.status == "passed", 1), else_=0)).label(
+                "completed"
+            ),
             func.sum(
                 func.case((TestRun.status.in_(["failed", "error"]), 1), else_=0)
             ).label("failed"),