feat(i18n): presentation extraction — t() call sites, data-i18n templates, locale selector

Route every application-owned presentation string through the i18n
core: t() call sites across the app/layers/ui/data/voice surfaces,
data-i18n* attributes in the src/ui/templates/*.html markup (applied at
boot by applyDocumentTranslations from src/standalone/application.js),
and the dock locale selector (runtime-rendered from the offered pair —
a single EN button while only English ships).

Rebased onto current main, where the extraction follows the module
splits: the shell wiring now lands in the owner modules
(panelChrome, visualSettings, locationNavigation, shareRestoration,
shellFeedback, applicationShell) and the voice status corpus in the
realtime* modules; scene status lives in director.js +
playbackAdapter.js.

Modules shared with the node runtime (loadingFeedback,
installationFeedback, regionalModel, keySetupCore, vessels ingestion)
stay environment-neutral English and localize at their browser render
sites (chip maps in shellFeedback/installations controls, the weather
table in cockpitBriefing, keySetupRequirementEnvVars compositions), so
the package-boundary graph stays clean; the browser boundary groups
now own the i18n modules they reach (scripts/package-boundaries.json).

src/creditKeyboard.js

@@ -2,6 +2,8 @@
  * Adds the keyboard semantics omitted by Cesium's href-less attribution links.
  * Cesium retains ownership of showing and hiding its required credit lightbox.
  */
+import { t } from './i18n/index.js';
+
 export function configureCreditKeyboardAccess(root = document) {
   const expand = root?.querySelector?.(
     '#cesium-credits .cesium-credit-expand-link',
@@ -19,7 +21,7 @@ export function configureCreditKeyboardAccess(root = document) {
   expand.setAttribute('aria-expanded', 'false');
   close.setAttribute('role', 'button');
   close.setAttribute('tabindex', '0');
-  close.setAttribute('aria-label', 'Close data attribution');
+  close.setAttribute('aria-label', t('shell.credits.closeAria'));
 
   if (expand.dataset.gevKeyboardReady === 'true') return true;
   expand.dataset.gevKeyboardReady = 'true';