feat(commands): whole-history dedupe + switchable, capped history

历史命令去重从「只跟最新一条比」改为「全历史去重」：重敲任意一条已有命令
时把原条目提到最前（刷新 lastUsedAt）而不是新插一条，历史里每个命令只出现一次。

新增两个设置（设置 → 终端）：
- 记录命令历史：关闭后不再记录新命令；已有历史保留，不清空
- 历史条数上限：默认 100，可配 1..500；写入按上限截断，读取也按当前
  上限截断（调低立即生效）

顺修一个暴露的既有 bug：logWrite 用 async appendFile，两次快速追加会
乱序落盘（line two 先于 line one）。改为按文件串行化追加。

测试：tests/commands-store.mjs 全历史去重 / 提到最前 / 上限生效 /
开关关闭不记录 / 关闭保留已有 / 恢复记录 / 越界上限夹紧，全部通过。

tests/electron-stub.cjs

@@ -1,12 +1,65 @@
-// Minimal electron stub for bundling src/main/pty.ts under plain Node
-// (tests/ssh-session-e2e.mjs). Only what broadcast.ts touches.
+// Minimal electron stub for bundling src/main/*.ts under plain Node
+// (tests/ssh-session-e2e.mjs, tests/commands-store.mjs). Only what the bundled
+// modules touch.
+//
+// `app.getPath('userData')` is configurable via `__setUserData` so a test can
+// point the settings store at a temp dir and exercise settings-driven behavior.
+let userDataPath = process.env.OT_STUB_USERDATA || ''
 module.exports = {
   BrowserWindow: {
     getAllWindows: () => []
   },
-  app: {},
-  ipcMain: {},
+  app: {
+    getPath: (name) => {
+      if (name === 'userData' && userDataPath) return userDataPath
+      throw new Error(`electron stub: app.getPath(${name}) is not configured`)
+    },
+    setLoginItemSettings: () => {},
+    isPackaged: false
+  },
+  ipcMain: {
+    handle: () => {},
+    on: () => {}
+  },
+  globalShortcut: {
+    register: () => true,
+    unregister: () => {},
+    unregisterAll: () => {},
+    isRegistered: () => false
+  },
+  webContents: {},
+  powerSaveBlocker: {
+    start: () => 1,
+    stop: () => {},
+    isStarted: () => false
+  },
+  shell: {
+    openPath: async () => ''
+  },
   safeStorage: {
     isEncryptionAvailable: () => false
+  },
+  nativeTheme: {
+    shouldUseDarkColors: true,
+    on: () => {}
+  },
+  Menu: {
+    buildFromTemplate: () => ({ popup: () => {} }),
+    setApplicationMenu: () => {}
+  },
+  Tray: class {
+    setToolTip() {}
+    setContextMenu() {}
+    on() {}
+    destroy() {}
+    static getBounds() {
+      return { x: 0, y: 0, width: 0, height: 0 }
+    }
+  },
+  nativeImage: {
+    createFromPath: () => ({ isEmpty: () => true, resize: () => ({}) })
+  },
+  __setUserData: (p) => {
+    userDataPath = p
   }
 }