chore: upgrade i18next 26, prettier 3, fontsource-variable, domhandler 6, lint-staged 17

- i18next 23->26 + react-i18next 15->17
- prettier 2->3, reformat all files
- replace @fontsource/inter with @fontsource-variable/inter 5, update import path
- domhandler 5->6 (aligns with transitive deps)
- lint-staged 16->17

src/app/hooks/useRoomEvent.ts

@@ -37,7 +37,7 @@ const useFetchEvent = (room: Room, eventId: string) => {
 export const useRoomEvent = (
   room: Room,
   eventId: string,
-  getLocally?: () => MatrixEvent | undefined
+  getLocally?: () => MatrixEvent | undefined,
 ) => {
   const event = useMemo(() => {
     if (getLocally) return getLocally();