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/contextSubscriptions.js

@@ -1,3 +1,4 @@
+import { t } from '../i18n/index.js';
 import {
   contextLayerEnableBlockReason,
   isExplicitUserIntentOrigin,
@@ -124,7 +125,12 @@ export function connectContextManager(manager) {
                 restoreError,
               );
             }
-            return `${entryMode === 'space-missions' ? 'Space Missions' : 'Context'} could not start because another layer did not stop cleanly`;
+            return t('cockpit.context.toastStartBlocked', {
+              mode:
+                entryMode === 'space-missions'
+                  ? t('cockpit.context.modeSpaceMissions')
+                  : t('cockpit.context.modeContext'),
+            });
           } finally {
             if (ownsNotificationToken) {
               this._userFacingContextNotificationTokens.delete(