Replace hardcoded French strings with i18n calls

Initialize i18n before auth so t() works when rendering
auth-dependent UI, and build the command palette lazily so
translations are loaded first. Bump service worker cache version.

frontend/js/sync.js

@@ -319,7 +319,7 @@ function _renderSyncPanel(panel) {
       const label = typeLabels[ev.type] || ev.type;
       let detail = ev.data.vaults ? ev.data.vaults.join(", ") : ev.data.vault || "";
       if (ev.type === "index_start") detail = `${ev.data.total_vaults} vaults à traiter`;
-      if (ev.type === "index_progress") detail = `${ev.data.vault} (${ev.data.files} fichiers)`;
+      if (ev.type === "index_progress") detail = t("sync.vault_files", {vault: ev.data.vault, files: ev.data.files});
       if (ev.type === "index_complete" && ev.data.total_files !== undefined) detail = `${ev.data.total_files} fichiers total`;
       html += `<div class="sync-panel__event">
         <span class="sync-panel__event-type">${label}</span>
@@ -367,7 +367,7 @@ function _renderAIStatusSection(panel) {
   let extIcon, extText, extClass;
   if (_aiProcessing) {
     extIcon = 'loader';
-    extText = 'Traitement en cours…';
+    extText = t('sync.processing');
     extClass = 'sync-panel__ai--processing';
   } else if (_aiConfigured === true) {
     extIcon = 'check-circle';
@@ -375,7 +375,7 @@ function _renderAIStatusSection(panel) {
     extClass = 'sync-panel__ai--active';
   } else if (_aiConfigured === false) {
     extIcon = 'x-circle';
-    extText = 'Aucun fournisseur';
+    extText = t('sync.no_provider');
     extClass = 'sync-panel__ai--inactive';
   } else {
     extIcon = 'help-circle';