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/useUserProfile.ts

@@ -36,7 +36,7 @@ export const useUserProfile = (userId: string): UserProfile => {
       setProfile({
         avatarUrl: info.avatar_url,
         displayName: info.displayname,
-      })
+      }),
     );
 
     user?.on(UserEvent.AvatarUrl, onAvatarChange);