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/contextLayerChanges.js

@@ -1,3 +1,4 @@
+import { t } from '../i18n/index.js';
 import {
   cockpitEntryAllowed,
   isExplicitUserIntentOrigin,
@@ -58,12 +59,22 @@ export function _handleContextLayerChange(change) {
       if (this._contextSessionSnapshot && !this._contextModeChanging) {
         this._contextMode = null;
         void this._trackContextLayerReaction(
-          this._runUserFacingContextAction(async (notificationToken) => {
-            await this._restoreContextSessionAfterLayerSettles(change.layerId, {
-              notificationToken,
-            });
-            return true;
-          }, 'Space Missions cancellation could not restore the previous layer state'),
+          this._runUserFacingContextAction(
+            async (notificationToken) => {
+              await this._restoreContextSessionAfterLayerSettles(
+                change.layerId,
+                {
+                  notificationToken,
+                },
+              );
+              return true;
+            },
+            {
+              localizedMessage: t(
+                'cockpit.context.toastMissionsCancelRestoreFailed',
+              ),
+            },
+          ),
         );
       }
     }
@@ -83,15 +94,19 @@ export function _handleContextLayerChange(change) {
       !this._userFacingContextNotificationTokens.has(change.notificationToken)
     ) {
       this.showToast(
-        change.reason ||
-          'That layer is unavailable in the current Context mode',
+        change.reason || t('cockpit.context.toastLayerUnavailable'),
       );
     }
     this._syncContextModeButtons();
     return;
   }
   if (change?.type === 'visibility-failed') {
-    const failureMessage = `${change.layerId} could not ${change.enabled ? 'start' : 'stop'} cleanly`;
+    const failureMessage = t('cockpit.context.toastLayerLifecycleFailed', {
+      layerId: change.layerId,
+      action: change.enabled
+        ? t('cockpit.context.actionStart')
+        : t('cockpit.context.actionStop'),
+    });
     // A failed direct Context-shell START has already had its siblings
     // cleared by the visibility guard. Wait outside the synchronous manager
     // notification for this queue to settle, then reconcile the complete