feat(web): i18n with react-i18next — Albanian default, English second

Add react-i18next with two key-parity-checked catalogs (sq default/fallback, en).
Active language driven by the logged-in user's stored preference (applied after
/me resolves); SQ/EN toggle in the header persists via PUT /api/auth/language.
Translate the booth (screen, pay/exit modal, active sessions, snapshots, status),
Login, ShiftControl, SiteSettings, PermitManager, TariffComposer.

SetupWizard deferred (its content is server-provided; needs backend catalog i18n).

apps/web/src/main.tsx

@@ -1,6 +1,7 @@
 import { StrictMode } from "react";
 import { createRoot } from "react-dom/client";
 import "./index.css";
+import "./lib/i18n/index.js"; // initialize i18next before the app renders
 import { App } from "./App.js";
 
 const rootEl = document.getElementById("root");