feat: add knowledge directory management for documents and FAQs

- Implemented directory validation in Create and Update knowledge document services.
- Added directory selection in document and FAQ edit dialogs with a new KnowledgeDirectoryPanel component.
- Enhanced API to support fetching, creating, updating, and deleting knowledge directories.
- Updated data models to include directory information for knowledge documents and FAQs.
- Added translations for directory-related messages in English and Chinese.

web/messages/zh-CN.json

@@ -1781,6 +1781,13 @@
     "baseSaveFailed": "保存知识库失败",
     "baseDeleted": "已删除知识库：{name}",
     "baseDeleteFailed": "删除知识库失败",
+    "loadDirectoriesFailed": "加载目录失败",
+    "directoryCreated": "已创建目录：{name}",
+    "directoryUpdated": "已更新目录：{name}",
+    "directoryDeleted": "已删除目录：{name}",
+    "directorySaveFailed": "保存目录失败",
+    "directoryDeleteFailed": "删除目录失败",
+    "directoryNameRequired": "目录名称不能为空",
     "rebuildStarted": "已开始重建知识库索引：{name}",
     "rebuildFailed": "重建知识库索引失败",
     "sortUpdated": "知识库排序已更新",
@@ -1791,6 +1798,21 @@
     "rebuildIndex": "重建索引",
     "deleting": "删除中...",
     "delete": "删除",
+    "directory": "目录",
+    "allContent": "全部内容",
+    "rootContent": "根目录内容",
+    "rootDirectory": "一级目录",
+    "parentDirectory": "上级目录",
+    "createDirectory": "新建目录",
+    "createSubDirectory": "新建子目录",
+    "editDirectory": "编辑目录",
+    "expandDirectory": "展开目录",
+    "collapseDirectory": "折叠目录",
+    "selectDirectory": "选择目录",
+    "searchDirectory": "搜索目录",
+    "emptyDirectory": "没有匹配的目录",
+    "directoryName": "目录名称",
+    "directoryNamePlaceholder": "请输入目录名称",
     "searchBase": "搜索知识库",
     "query": "查询",
     "emptyBases": "没有匹配的知识库",