fix: restore mx declarations removed by cleanup script

The automated unused-var cleanup incorrectly removed const mx = useMatrixClient()
from MessageDeleteItem and ReportMessage components in Message.tsx. Both components
use mx inside their useCallback closures (mx.redactEvent, mx.reportEvent). This
caused a ReferenceError crash on the messages view in production.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/features/room/message/Message.tsx

@@ -445,12 +445,13 @@ export const MessageDeleteItem = as<
     onClose?: () => void;
   }
 >(({ room, mEvent, onClose, ...props }, ref) => {
+  const mx = useMatrixClient();
   const [open, setOpen] = useState(false);
   const [deleteState, deleteMessage] = useAsyncCallback(
     useCallback(
       (eventId: string, reason?: string) =>
         mx.redactEvent(room.roomId, eventId, undefined, reason ? { reason } : undefined),
-      [room],
+      [mx, room],
     ),
   );
 
@@ -572,12 +573,13 @@ export const MessageReportItem = as<
     onClose?: () => void;
   }
 >(({ room, mEvent, onClose, ...props }, ref) => {
+  const mx = useMatrixClient();
   const [open, setOpen] = useState(false);
   const [reportState, reportMessage] = useAsyncCallback(
     useCallback(
       (eventId: string, score: number, reason: string) =>
         mx.reportEvent(room.roomId, eventId, score, reason),
-      [room],
+      [mx, room],
     ),
   );