Add zh/en i18n and follow DSH locale.bind for UI.

Wire API/delivery/tool strings through lib/i18n.js, and make the sidebar use ctx.locale.bind plus locale/change so English host preference no longer stays frozen on Chinese.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/index.js

@@ -74,6 +74,15 @@ export {
   resolveCreateOrigin,
   resolveMirrorSession,
 } from './delivery.js'
+export {
+  DEFAULT_LOCALE,
+  MESSAGES,
+  TITLE_PREFIX_EN,
+  apiError,
+  normalizeLocale,
+  resolveLocale,
+  t,
+} from './i18n.js'
 
 function loadPkg(id) {
   const homes = [