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/ui/clearLayersControl.js

@@ -1,3 +1,5 @@
+import { t } from '../i18n/index.js';
+
 /** Keep the clear action focusable while busy; the caller owns its transaction. */
 export function bindClearLayersControl(button, clear) {
   let destroyed = false;
@@ -12,7 +14,9 @@ export function bindClearLayersControl(button, clear) {
       button.setAttribute('aria-busy', String(busy));
       button.setAttribute(
         'aria-label',
-        busy ? 'Clearing selected data layers' : 'Clear selected data layers',
+        busy
+          ? t('cockpit.actions.clearLayersBusyAria')
+          : t('shell.actions.clearLayers.ariaLabel'),
       );
     },
     destroy() {