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/state/sessions.ts

@@ -33,7 +33,7 @@ export function setFallbackSession(
   accessToken: string,
   deviceId: string,
   userId: string,
-  baseUrl: string
+  baseUrl: string,
 ) {
   localStorage.setItem('cinny_access_token', accessToken);
   localStorage.setItem('cinny_device_id', deviceId);