新增 pc-client：畅联 PC 端工程（Electron+React，按确认效果图改造，B-59）

- 基于 openim-electron-demo 改造：工号+密码登录（自研账号服务）、会话列表/聊天窗/通讯录界面重做
- 文字/语音/文件/图片消息、文件拖拽发送、表情面板、一对一语音通话（LiveKit）
- RTC 令牌对接账号服务带鉴权版 /api/rtc_token（Bearer imToken + {room,identity}）
- account-service: CORS Allow-Headers 补 authorization（浏览器/渲染进程跨域调 rtc_token 需要）
- 附本地 mock 账号服务（scripts/mock-account-server.js）与截图联调脚本

pc-client/electron/main/menuManage.ts

@@ -0,0 +1,55 @@
+import { app, Menu } from "electron";
+import { t } from "i18next";
+import { isMac } from "../utils";
+
+const createAppMenu = () => {
+  if (isMac) {
+    const template: Electron.MenuItemConstructorOptions[] = [
+      {
+        label: app.getName(),
+        submenu: [
+          { label: t("system.about"), role: "about" },
+          { type: "separator" },
+          { label: t("system.hide"), role: "hide" },
+          { type: "separator" },
+          {
+            label: t("system.quit"),
+            click: () => {
+              global.forceQuit = true;
+              app.quit();
+            },
+          },
+        ],
+      },
+      {
+        label: t("system.fastKeys"),
+        submenu: [
+          { label: t("system.copy"), role: "copy", accelerator: "CmdOrCtrl+C" },
+          { label: t("system.paste"), role: "paste", accelerator: "CmdOrCtrl+V" },
+          { label: t("system.cut"), role: "cut", accelerator: "CmdOrCtrl+X" },
+          { label: t("system.undo"), role: "undo", accelerator: "CmdOrCtrl+Z" },
+          { label: t("system.redo"), role: "redo", accelerator: "CmdOrCtrl+Y" },
+          {
+            label: t("system.selectAll"),
+            role: "selectAll",
+            accelerator: "CmdOrCtrl+A",
+          },
+        ],
+      },
+      {
+        label: t("system.window"),
+        role: "window",
+        submenu: [
+          { label: t("system.minimize"), role: "minimize", accelerator: "CmdOrCtrl+W" },
+          { label: t("system.close"), role: "close" },
+        ],
+      },
+    ];
+
+    Menu.setApplicationMenu(Menu.buildFromTemplate(template));
+  } else {
+    Menu.setApplicationMenu(null);
+  }
+};
+
+export default createAppMenu;