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/useAutoExpandDir.ts

@@ -0,0 +1,26 @@
+import { useEffect } from 'react'
+import { useSidebarStore } from '../stores/sidebarStore'
+
+/**
+ * AR-02: 自动展开到活动文件所在的目录
+ */
+export function useAutoExpandDir(activeFilePath: string | null) {
+  const rootPath = useSidebarStore(s => s.rootPath)
+  const expandDirs = useSidebarStore(s => s.expandDirs)
+
+  useEffect(() => {
+    if (!activeFilePath || !rootPath) return
+    const norm = (p: string) => p.replace(/\\/g, '/')
+    if (!norm(activeFilePath).startsWith(norm(rootPath))) return
+
+    const dirsToExpand: string[] = []
+    let dir = activeFilePath.replace(/[/\\][^/\\]+$/, '')
+    let prev = ''
+    while (dir && dir.length >= rootPath.length && dir !== rootPath && dir !== prev) {
+      prev = dir
+      dirsToExpand.push(dir)
+      dir = dir.replace(/[/\\][^/\\]+$/, '')
+    }
+    if (dirsToExpand.length > 0) expandDirs(dirsToExpand)
+  }, [activeFilePath, rootPath, expandDirs])
+}