v0.2.0: 全面代码质量优化

- ESLint flat config + Prettier + EditorConfig
- Markdown处理器LRU缓存
- Zustand选择器优化减少重渲染
- CodeMirror Compartment主题热切换
- Preview防抖(150ms) + IndexedDB去抖(500ms)
- 组件拆分: App.tsx 310→104行, Sidebar.tsx 244→90行
- 统一错误处理 errorHandler.ts
- ConfirmDialog替代原生confirm
- LoadingSpinner加载状态
- Toast多条堆叠+类型区分
- 可访问性增强(ARIA属性、键盘导航)
- Vitest测试框架(78个测试用例)
- Git hooks(husky + lint-staged)
- 项目文档(README.md, CONTRIBUTING.md)

src/renderer/hooks/useFolderOperations.ts

@@ -0,0 +1,54 @@
+import { useEffect, useCallback } from 'react'
+import { useSidebarStore } from '../stores/sidebarStore'
+import { useEditorStore } from '../stores/editorStore'
+
+/**
+ * AR-02: 从 Sidebar.tsx 提取的文件夹操作逻辑
+ * UX-02: 添加目录加载 loading 状态
+ */
+export function useFolderOperations() {
+  const rootPath = useSidebarStore(s => s.rootPath)
+  const setRootPath = useSidebarStore(s => s.setRootPath)
+  const setTree = useSidebarStore(s => s.setTree)
+  const expandDirs = useSidebarStore(s => s.expandDirs)
+  const setLoading = useEditorStore(s => s.setLoading)
+
+  const handleOpenFolder = useCallback(async () => {
+    if (!window.electronAPI) return
+    const result = await window.electronAPI.openFolderDialog()
+    if (!result.canceled && result.filePaths[0]) {
+      const dirPath = result.filePaths[0]
+      setRootPath(dirPath)
+      expandDirs([dirPath])
+      setLoading('dir-load', true)
+      try {
+        const dirTree = await window.electronAPI.readDirTree(dirPath)
+        if (dirTree.success && dirTree.tree) {
+          setTree(dirTree.tree)
+          window.electronAPI.watchDir(dirPath)
+        }
+      } finally {
+        setLoading('dir-load', false)
+      }
+    }
+  }, [setRootPath, setTree, expandDirs, setLoading])
+
+  const refreshTree = useCallback(async () => {
+    if (!rootPath || !window.electronAPI) return
+    setLoading('dir-load', true)
+    try {
+      const result = await window.electronAPI.readDirTree(rootPath)
+      if (result.success && result.tree) setTree(result.tree)
+    } finally {
+      setLoading('dir-load', false)
+    }
+  }, [rootPath, setTree, setLoading])
+
+  useEffect(() => {
+    if (!window.electronAPI) return
+    const unsubscribe = window.electronAPI.onDirChanged(() => refreshTree())
+    return unsubscribe
+  }, [refreshTree])
+
+  return { handleOpenFolder }
+}