docs(wiki): reconcile with session — booth console, i18n, live WS

File concept pages for the operator-UI architecture ([[booth-console]]: stack,
/api/ws live feed, anti-CSWSH) and [[i18n]] (per-user server-stored language;
resolves a dangling code-comment link). Qualify the stale 'plain React' note on
react-vite-spa. Backfill log entries for the live WebSocket, frontend foundation,
and i18n builds (which had none), plus a reconciliation lint entry. Catalog
booth-exit-flow + the two new pages in index; fix the concept count (27→41).

wiki/concepts/i18n.md

@@ -0,0 +1,55 @@
+---
+type: concept
+tags: [parking, frontend, i18n, localization]
+sources: []
+updated: 2026-06-18
+status: open
+---
+
+# Internationalization (i18n)
+
+The operator UI ships in **two languages: Albanian (default) and English**. Language is a
+**per-user preference stored server-side** and loaded on login — not a browser/localStorage setting,
+not a site-wide one. So an operator's choice follows their account and is restored on every login from
+any booth. (Decided + built 2026-06-18.)
+
+## Decisions
+
+- **Albanian is the default and fallback.** English is the second language. A missing English key
+  falls back to Albanian.
+- **Per-user, server-side preference.** `users.language` (`'sq' | 'en'`, default `'sq'`; migration
+  0003). Returned from `/api/auth/login` and `/api/auth/me`, and changed via **`PUT /api/auth/language`**
+  (self-service, any signed-in role). It is **deliberately NOT in the JWT** (identity/role only) — so
+  changing language is a DB write + immediate `/me`, with no token refresh / re-login. See
+  [[local-jwt-auth]].
+- **Library: react-i18next** (i18next). Chosen over a hand-rolled `t()` for pluralization,
+  interpolation, and headroom beyond two languages. The active language is applied after `/me`
+  resolves (App effect on `user.language`); the header **SQ/EN toggle** switches instantly *and*
+  persists.
+- **Printed tickets/receipts stay Albanian.** Customer-facing paper is **independent** of the
+  operator's UI language — an operator reading the UI in English still prints Albanian tickets. The
+  print strings live in the device driver's `STR` table ([[ticket-encoding]], [[site-metadata]]); can
+  become a `site_config.print_language` setting later if a site ever needs English receipts.
+
+## As-built (2026-06-18)
+
+- **Backend:** `users.language` + the three auth touch-points above (`apps/server/src/routes/auth.ts`).
+- **Frontend:** `apps/web/src/lib/i18n/` — `sq.ts` (default/fallback), `en.ts`, and `index.ts` (init +
+  `setLanguage()`). **Type-safe key parity:** `Catalog` is the *shape* of `sq` with string-typed
+  values, so TypeScript forces `en.ts` to supply every key (and the build fails on a missing/typo'd
+  key). Keys are dot-namespaced by area (`common`, `nav`, `status`, `auth`, `booth`, `pay`, `shift`,
+  `site`, `permits`, `tariff`).
+- **Translated screens:** the booth ([[booth-console]] — screen, pay/exit modal, active sessions,
+  snapshots, status), Login, ShiftControl, SiteSettings, PermitManager, TariffComposer.
+
+## Open / deferred
+
+- **SetupWizard is NOT translated** (deliberate). Its content is mostly **server-provided** — driver
+  labels and config-field labels/help come from the backend device-catalog API ([[device-registry]],
+  [[first-run-setup]]). Translating only its static chrome would leave a half-English screen; it's
+  deferred until **backend catalog i18n** is scoped, then chrome + catalog localize together.
+- **Server API error strings** are still English (surfaced raw in the UI). v1 relies on the
+  client mapping known errors; a fuller approach would translate by error *code*, not message.
+- **Behaviour note (not a bug):** a *hard navigation* (new URL) re-bootstraps the language from the
+  user's stored preference via `/me` — so an un-persisted toggle resets. Correct: the stored pref
+  wins. The toggle persists via the PUT, so it survives once saved.