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/src/main.tsx

@@ -0,0 +1,21 @@
+import "./processShim";
+import "./index.scss";
+import "./i18n/index";
+
+import log from "electron-log/renderer";
+import ReactDOM from "react-dom/client";
+
+import App from "./App";
+import { isSaveLog } from "./config";
+
+if (window.electronAPI && isSaveLog) {
+  const sdkLogger = log.scope("openim-sdk-core");
+  console.debug = sdkLogger.debug.bind(sdkLogger);
+  const rendererLogger = log.scope("renderer");
+  console.info = rendererLogger.info.bind(rendererLogger);
+  console.error = rendererLogger.error.bind(rendererLogger);
+}
+
+ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(<App />);
+
+postMessage({ payload: "removeLoading" }, "*");