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/e2e/debug-page.cjs

@@ -0,0 +1,21 @@
+const { chromium } = require("@playwright/test");
+
+(async () => {
+  const browser = await chromium.launch({
+    executablePath:
+      "C:/Users/MoBai/AppData/Local/ms-playwright/chromium_headless_shell-1228/chrome-headless-shell-win64/chrome-headless-shell.exe",
+  });
+  const page = await browser.newPage({ viewport: { width: 1200, height: 800 } });
+  page.on("console", (msg) => console.log("[" + msg.type() + "]", msg.text().slice(0, 300)));
+  page.on("pageerror", (err) => console.log("[pageerror]", String(err).slice(0, 500)));
+
+  await page.goto("http://localhost:5173/");
+  await page.waitForTimeout(6000);
+  const html = await page.content();
+  console.log("body length:", html.length);
+  console.log(html.slice(0, 800));
+  await browser.close();
+})().catch((e) => {
+  console.error(e);
+  process.exit(1);
+});