fix: use sqlalchemy.case() instead of func.case() for conditional aggregation

func.case() is not valid SQLAlchemy - case() must be imported directly
from sqlalchemy. This was causing TypeError on /api/v1/admin/background-tasks/tasks/stats.

🤖 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

@@ -6,7 +6,7 @@ Service for monitoring background tasks across the system
 
 from datetime import UTC, datetime
 
-from sqlalchemy import desc, func
+from sqlalchemy import case, desc, func
 from sqlalchemy.orm import Session
 
 from models.database.marketplace_import_job import MarketplaceImportJob
@@ -55,10 +55,10 @@ class BackgroundTasksService:
         stats = db.query(
             func.count(MarketplaceImportJob.id).label("total"),
             func.sum(
-                func.case((MarketplaceImportJob.status == "processing", 1), else_=0)
+                case((MarketplaceImportJob.status == "processing", 1), else_=0)
             ).label("running"),
             func.sum(
-                func.case(
+                case(
                     (
                         MarketplaceImportJob.status.in_(
                             ["completed", "completed_with_errors"]
@@ -69,7 +69,7 @@ class BackgroundTasksService:
                 )
             ).label("completed"),
             func.sum(
-                func.case((MarketplaceImportJob.status == "failed", 1), else_=0)
+                case((MarketplaceImportJob.status == "failed", 1), else_=0)
             ).label("failed"),
         ).first()
 
@@ -96,14 +96,14 @@ class BackgroundTasksService:
 
         stats = db.query(
             func.count(TestRun.id).label("total"),
-            func.sum(func.case((TestRun.status == "running", 1), else_=0)).label(
+            func.sum(case((TestRun.status == "running", 1), else_=0)).label(
                 "running"
             ),
-            func.sum(func.case((TestRun.status == "passed", 1), else_=0)).label(
+            func.sum(case((TestRun.status == "passed", 1), else_=0)).label(
                 "completed"
             ),
             func.sum(
-                func.case((TestRun.status.in_(["failed", "error"]), 1), else_=0)
+                case((TestRun.status.in_(["failed", "error"]), 1), else_=0)
             ).label("failed"),
             func.avg(TestRun.duration_seconds).label("avg_duration"),
         ).first()