feat(scheduler): implement scheduler service for background tasks and credit refills; add endpoints for admin control

app/routes/main.py

@@ -8,6 +8,7 @@ from app.services.decorators import (
     require_credits,
     require_role,
 )
+from app.services.scheduler_service import scheduler_service
 
 bp = Blueprint("main", __name__)
 
@@ -84,3 +85,19 @@ def expensive_operation() -> dict[str, str]:
         "user": user["email"],
         "operation_cost": 10,
     }
+
+
+@bp.route("/admin/scheduler/status")
+@require_auth
+@require_role("admin")
+def scheduler_status() -> dict:
+    """Get scheduler status (admin only)."""
+    return scheduler_service.get_scheduler_status()
+
+
+@bp.route("/admin/credits/refill", methods=["POST"])
+@require_auth
+@require_role("admin")
+def manual_credit_refill() -> dict:
+    """Manually trigger credit refill for all users (admin only)."""
+    return scheduler_service.trigger_credit_refill_now()