refactor: 移除自定义状态栏 — 使用 MetonaEditor 自带底栏

- editor 自带底栏（wordCount: true）已显示字符数/词数/行数/阅读时间
- 删除自定义 StatusBar 组件、editorStore 的 stats/cursor 状态与事件绑定
- 保留 zenMode 同步（Toolbar 专注按钮消费）；自动保存状态由 Toolbar 按钮显示

src/renderer/stores/editorStore.ts

@@ -16,21 +16,6 @@ export function getMetonaEditor(): MarkdownEditor | null {
 
 const THEME_CYCLE: ThemeMode[] = ['light', 'dark', 'warm']
 
-/** v0.6.0: 编辑器实时状态（由 Editor 组件绑定事件写入，状态栏消费） */
-export interface EditorLiveStats {
-  characters: number
-  words: number
-  chineseChars: number
-  englishWords: number
-  lines: number
-  readingTime: number
-}
-
-export interface EditorCursor {
-  line: number
-  column: number
-}
-
 interface EditorState {
   viewMode: ViewMode
   themeMode: ThemeMode
@@ -38,9 +23,7 @@ interface EditorState {
   externallyModified: { filePath: string } | null
   // UX-02: 全局加载状态
   loadingStates: Record<string, boolean>
-  // v0.6.0: 编辑器实时状态
-  stats: EditorLiveStats | null
-  cursor: EditorCursor | null
+  // v0.6.0: Zen 模式状态（Toolbar 消费）
   zenMode: boolean
 
   setViewMode: (mode: ViewMode) => void
@@ -50,9 +33,6 @@ interface EditorState {
   // UX-02: 加载状态管理
   setLoading: (key: string, loading: boolean) => void
   isLoading: (key: string) => boolean
-  // v0.6.0: 编辑器状态同步
-  setStats: (stats: EditorLiveStats | null) => void
-  setCursor: (cursor: EditorCursor | null) => void
   setZenMode: (zen: boolean) => void
 }
 
@@ -61,8 +41,6 @@ export const useEditorStore = create<EditorState>((set, get) => ({
   themeMode: 'light',
   externallyModified: null,
   loadingStates: {},
-  stats: null,
-  cursor: null,
   zenMode: false,
 
   setViewMode: (mode: ViewMode) => set({ viewMode: mode }),
@@ -80,7 +58,5 @@ export const useEditorStore = create<EditorState>((set, get) => ({
       loadingStates: { ...state.loadingStates, [key]: loading },
     })),
   isLoading: (key: string) => get().loadingStates[key] ?? false,
-  setStats: (stats: EditorLiveStats | null) => set({ stats }),
-  setCursor: (cursor: EditorCursor | null) => set({ cursor }),
   setZenMode: (zenMode: boolean) => set({ zenMode }),
 }))