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/useSettingsInit.ts

@@ -0,0 +1,48 @@
+import { useEffect, useRef } from 'react'
+import { useEditorStore } from '../stores/editorStore'
+import { useSidebarStore } from '../stores/sidebarStore'
+import { settingsRepository } from '../db/settingsRepository'
+import { logError } from '../lib/errorHandler'
+
+/**
+ * AR-04: 统一设置加载 hook
+ * 一次性从 IndexedDB 加载所有设置，分发到各 store
+ * 替代 useTheme、useSettings、sidebarStore.loadFromDB 各自独立加载的模式
+ */
+export function useSettingsInit() {
+  const setDarkMode = useEditorStore(s => s.setDarkMode)
+  const setViewMode = useEditorStore(s => s.setViewMode)
+  const isInitialized = useRef(false)
+
+  useEffect(() => {
+    if (isInitialized.current) return
+    isInitialized.current = true
+
+    settingsRepository.load()
+      .then((settings) => {
+        // 主题
+        const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches
+        const darkMode = settings.darkMode !== undefined ? settings.darkMode : prefersDark
+        setDarkMode(darkMode)
+        document.documentElement.classList.toggle('dark', darkMode)
+
+        // 视图模式
+        setViewMode(settings.viewMode ?? 'editor')
+
+        // Sidebar 设置（直接分发，避免 sidebarStore 再次读取 IndexedDB）
+        const sidebarStore = useSidebarStore.getState()
+        if (!sidebarStore._loaded) {
+          useSidebarStore.setState({
+            isVisible: !settings.sidebarCollapsed,
+            sidebarWidth: settings.sidebarWidth,
+            _loaded: true
+          })
+        }
+      })
+      .catch((error: unknown) => {
+        logError('加载设置失败', error)
+      })
+  }, [setDarkMode, setViewMode])
+
+  return { isInitialized }
+}