Switch language in place, without a reload

Choosing a language in the picker now applies it at once. The choice is
stored and ?lang is kept in step through replaceState, and the picker keeps
focus.

Code that writes translated text itself re-presents it on a switch:
onLocaleChange() lets an owner listen, removed at teardown, and status
writers hand over a function of the locale (voice cards, scene director,
SDR, draw hints, imagery split, map sources, Bhote Koshi media) so the
words are rebuilt rather than re-sent. The HUD, cockpit, radio, CCTV,
launch, awareness and credit texts follow the same hook, and
applyDocumentTranslations can be applied again without undoing text code
wrote since.

The unsaved-work registry and persistLocaleAndReload existed only to guard
the reload, so they go, with their catalog entries.

docs/CURRENT-STATE.md

@@ -3854,10 +3854,10 @@ Shipped locales: **en** (source and fallback), **de**, **es**, **fr**, **it**, *
   select `zh-Hant`. Explicit `Hans` selects `zh-CN` regardless of region. `?lang=` is not stored, and share links drop
   it, so a recipient keeps their own language. The globe picker in the
   bottom-right corner (`src/ui/localePicker.js`) stores the choice, drops
-  `?lang=` (keeps it only when storage is blocked) and reloads. It asks first
-  when the reload would lose work registered with `registerUnsavedWork`:
-  unsaved keys or CCTV calibration, Draw marks, imported map files, the open
-  cockpit, a voice session.
+  `?lang=` (keeps it only when storage is blocked) and switches in place:
+  views re-render, code that published translated text words it again through
+  `onLocaleChange`, and `<html lang>`/`dir` and the page's `data-i18n` markup
+  follow. Nothing is lost; a toast already on screen keeps its words.
 - **Gate.** `npm run i18n` (and `src/i18n/catalog.test.mjs` under `npm test`)
   extracts every message and fails on missing, empty, unused,
   placeholder-mismatched, still-English (plural forms included) or