feat(viewer): album page with locale fallback and timezone display

Co-Authored-By: Claude Code <noreply@anthropic.com>

apps/viewer/src/components/LocaleSwitcher.vue

@@ -1,7 +1,7 @@
 <script setup lang="ts">
 import { computed } from 'vue';
 import { useI18n } from 'vue-i18n';
-import { setLocale, type ViewerLocale } from '../i18n';
+import { LOCALE_STORAGE_KEY, type ViewerLocale } from '../i18n';
 
 const { locale, t } = useI18n();
 
@@ -9,8 +9,17 @@ const nextLocale = computed<ViewerLocale>(() => (locale.value === 'zh-CN' ? 'en'
 // 按钮始终显示目标语言的自称，便于不识当前语言的用户发现
 const nextLabel = computed(() => (nextLocale.value === 'zh-CN' ? '中文' : 'English'));
 
+// 直接写当前 composer（可写 locale）：与注入的 i18n 实例解耦——组件测试可挂载
+// 独立实例而不被运行时单例牵制。持久化随切换写入，写失败不阻断。
+// 注意先取 next 再赋值：赋值后 nextLocale 已重算为目标的对侧。
 function switchLocale(): void {
-  setLocale(nextLocale.value);
+  const next = nextLocale.value;
+  locale.value = next;
+  try {
+    localStorage.setItem(LOCALE_STORAGE_KEY, next);
+  } catch {
+    // 忽略持久化失败
+  }
 }
 </script>