Remove dependency resolution override for React 19 types (#39569)

Co-authored-by: ChaosExAnima <ChaosExAnima@users.noreply.github.com>

app/javascript/mastodon/components/navigation_focus_target/index.tsx

@@ -20,8 +20,9 @@ export type FocusTarget =
   | boolean
   | (typeof FOCUS_TARGET)[keyof typeof FOCUS_TARGET];
 
-const FocusTargetContext =
-  createContext<React.MutableRefObject<FocusTarget> | null>(null);
+const FocusTargetContext = createContext<React.RefObject<FocusTarget> | null>(
+  null,
+);
 
 /**
  * `FocusTargetProvider` keeps track of whether focus should be