fix: suppress unhandled promise rejections from fire-and-forget useEffect loads

useAsync re-throws errors after storing them in state — correct for awaited
callers but causes unhandled rejections when load() is called without .catch()
in useEffects. The error is already captured in AsyncState.Error so the
re-throw provides no additional value in these fire-and-forget patterns.

Fixes JAVASCRIPT-REACT-M (Sentry: Media download failed: 401 Unauthorized)

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

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

@@ -106,7 +106,7 @@ export function EditHistoryModal({ room, mEvent, onClose }: EditHistoryModalProp
   );
 
   useEffect(() => {
-    fetchHistory();
+    void fetchHistory().catch(() => undefined);
   }, [fetchHistory]);
 
   const formatTs = (ts: number): string => {