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/index.ts

@@ -0,0 +1,28 @@
+import { app } from "electron";
+import { join } from "node:path";
+import { createMainWindow } from "./windowManage";
+import { createTray } from "./trayManage";
+import { setIpcMainListener } from "./ipcHandlerManage";
+import { setAppGlobalData, setAppListener, setSingleInstance } from "./appManage";
+import createAppMenu from "./menuManage";
+import { isLinux } from "../utils";
+import { getLogger } from "../utils/log";
+import { initI18n } from "../i18n";
+
+export const logger = getLogger(join(app.getPath("userData"), `/OpenIMData/logs`));
+
+const init = () => {
+  initI18n();
+  createMainWindow();
+  createAppMenu();
+  createTray();
+};
+
+setAppGlobalData();
+setIpcMainListener();
+setSingleInstance();
+setAppListener(init);
+
+app.whenReady().then(() => {
+  isLinux ? setTimeout(init, 300) : init();
+});