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/pages/pathSearchParam.ts

@@ -7,7 +7,7 @@ export const getRoomSearchParams: SearchParamsGetter<_RoomSearchParams> = (searc
 });
 
 export const getDirectCreateSearchParams: SearchParamsGetter<DirectCreateSearchParams> = (
-  searchParams
+  searchParams,
 ) => ({
   userId: searchParams.get('userId') ?? undefined,
 });