fix(desktop): 优化窗口管理和图标支持

- 添加Menu导入并隐藏默认应用菜单
- 新增窗口图标解析函数，支持Windows打包场景
- 修改窗口背景色为浅蓝白色#f4f8ff
- 启用autoHideMenuBar提升用户体验
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/desktop/src/main/create-window.ts

-import { BrowserWindow, app } from "electron";
+import { BrowserWindow, Menu, app } from "electron";
 import path from "node:path";
 import { pathToFileURL } from "node:url";
 
@@ -10,14 +10,25 @@ function resolveRendererEntry(): string {
   return path.join(app.getAppPath(), "dist", "renderer", "index.html");
 }
 
+function resolveWindowIcon(): string | undefined {
+  return process.platform === "win32"
+    ? (app.isPackaged
+      ? path.join(process.resourcesPath, "brand-icon.ico")
+      : path.join(app.getAppPath(), "build", "icons", "brand-icon.ico"))
+    : undefined;
+}
+
 export function createMainWindow(smokeEnabled = false): BrowserWindow {
+  Menu.setApplicationMenu(null);
   const preloadPath = path.join(__dirname, "..", "preload", "index.js");
   const window = new BrowserWindow({
     width: 1400,
     height: 920,
     minWidth: 960,
     minHeight: 640,
-    backgroundColor: "#0f172a",
+    backgroundColor: "#f4f8ff",
+    autoHideMenuBar: true,
+    icon: resolveWindowIcon(),
     webPreferences: {
       additionalArguments: smokeEnabled ? ["--qjc-smoke"] : [],
       contextIsolation: true,