release: v0.4.0 — MetonaEditor 集成与架构重构

feat(editor): 将 Milkdown/ProseMirror 替换为 @metona-team/metona-editor v0.1.3
  - 三模式视图 (edit/split/preview) 由编辑器内置工具栏切换
  - searchReplace + imagePaste 预设插件
  - unified/rehype 渲染管线通过 render 钩子集成
  - 主题双向同步 (应用暗色模式 ↔ 编辑器主题)

feat(toast): metona-toast 迁移为 @metona-team/metona-toast v2.0.1

refactor: 删除冗余组件与代码
  - 移除 SourceEditor、Preview、SearchReplace、EditorToolbar、useMilkdown
  - 移除 StatusBar 组件及状态栏扩展架构（编辑器内置底栏替代）
  - 移除 useSettings、useStatusBarItem、useStatusBarItems、statusBarStore
  - 移除 EditMode/PreviewMode/SourceMode 图标

refactor(ui): 简化布局
  - 工具栏移除模式切换按钮，新增自动保存开关
  - useKeyboard 移除 Ctrl+1/2/3/B/I 快捷键
  - Editor 三模式统一由 MetonaEditor 容器渲染

chore: 版本号 v0.3.13 → v0.4.0
docs: 全面更新 README/DESIGN/CONTRIBUTING/DEVSETUP

src/renderer/hooks/useKeyboard.ts

@@ -1,19 +1,18 @@
 import { useEffect, useCallback } from 'react'
 import { useTabStore } from '../stores/tabStore'
-import { useEditorStore } from '../stores/editorStore'
 
+/**
+ * 全局键盘快捷键 hook。
+ * MetonaEditor 内置工具栏处理格式化和模式切换（Ctrl+B/I/1/2/3），
+ * 本 hook 仅处理应用级快捷键。
+ */
 export function useKeyboard(handleOpenFile: () => void, handleSave: () => void, handleSaveAs: () => void) {
-  const setViewMode = useEditorStore(s => s.setViewMode)
-
   const handleKeydown = useCallback((e: KeyboardEvent) => {
     const isCtrl = e.ctrlKey || e.metaKey
 
     if (isCtrl && e.key === 'o') { e.preventDefault(); handleOpenFile(); return }
     if (isCtrl && e.key === 's' && !e.shiftKey) { e.preventDefault(); handleSave(); return }
     if (isCtrl && e.shiftKey && e.key === 'S') { e.preventDefault(); handleSaveAs(); return }
-    if (isCtrl && e.key === '1') { e.preventDefault(); setViewMode('editor'); return }
-    if (isCtrl && e.key === '2') { e.preventDefault(); setViewMode('preview'); return }
-    if (isCtrl && e.key === '3') { e.preventDefault(); setViewMode('source'); return }
 
     const tabState = useTabStore.getState()
     if (isCtrl && e.key === 't') { e.preventDefault(); tabState.createTab(null, ''); return }
@@ -28,7 +27,6 @@ export function useKeyboard(handleOpenFile: () => void, handleSave: () => void,
       e.preventDefault()
       const { tabs, activeTabId, mruStack } = tabState
       if (tabs.length > 1) {
-        // mruStack[0] 是最近一个被切走的标签（即上一个活动标签）
         if (mruStack.length > 0) {
           const targetId = mruStack[0]
           if (tabs.find(t => t.id === targetId)) {
@@ -36,7 +34,6 @@ export function useKeyboard(handleOpenFile: () => void, handleSave: () => void,
             return
           }
         }
-        // MRU 栈为空或不合法时回退到顺序切换
         const idx = tabs.findIndex(t => t.id === activeTabId)
         const next = e.shiftKey
           ? (idx - 1 + tabs.length) % tabs.length
@@ -45,7 +42,7 @@ export function useKeyboard(handleOpenFile: () => void, handleSave: () => void,
       }
       return
     }
-  }, [handleOpenFile, handleSave, handleSaveAs, setViewMode])
+  }, [handleOpenFile, handleSave, handleSaveAs])
 
   useEffect(() => {
     document.addEventListener('keydown', handleKeydown)