[fix] cleanup task to other thread

adapter/http/fastapi/app.py

@@ -75,13 +75,25 @@ def _build_shutdown_handler(
     container: AppContainer,
 ) -> Callable[[], Awaitable[None]]:
     async def shutdown() -> None:
+        errors: list[Exception] = []
+
         try:
             await _stop_cleanup_loop(app)
-        finally:
-            try:
-                _uninstrument_app(app)
-            finally:
-                container.shutdown()
+        except Exception as exc:
+            errors.append(exc)
+
+        try:
+            _uninstrument_app(app)
+        except Exception as exc:
+            errors.append(exc)
+
+        try:
+            container.shutdown()
+        except Exception as exc:
+            errors.append(exc)
+
+        if errors:
+            raise ExceptionGroup('app shutdown failed', errors)
 
     return shutdown
 
@@ -94,7 +106,9 @@ async def _run_cleanup_loop(
 
     while not stop_event.is_set():
         try:
-            container.usecases.cleanup_expired_sandboxes.execute()
+            await asyncio.to_thread(
+                container.usecases.cleanup_expired_sandboxes.execute
+            )
         except Exception as exc:
             container.observability.logger.error(
                 'sandbox_cleanup_failed',