feat: optimize key list with list/tree views

- Add list view (flat) and tree view (hierarchical)
- Tree view shows folder expand/collapse with key count
- Add view mode toggle button
- Add i18n support for all key list text

src/i18n/locales/zh-CN.ts

@@ -71,6 +71,9 @@ export default {
     selected: '已选 {n} 项',
     selectKey: '选择一个键查看详情',
     unsupported: '类型 "{type}" 查看器尚未实现',
+    patternPlaceholder: '键模式 (例如 user:*)',
+    switchTree: '切换到树状视图',
+    switchList: '切换到列表视图',
   },
   types: {
     string: '字符串',