refactor: 统一端口配置，通过 IPC 获取而非硬编码

electron/main.ts

@@ -366,6 +366,10 @@ ipcMain.handle('xc-opencode-web-get-status', () => {
   return xcOpenCodeWebService.getStatus();
 });
 
+ipcMain.handle('xc-opencode-web-get-port', () => {
+  return { port: xcOpenCodeWebService.port };
+});
+
 ipcMain.handle('xc-opencode-web-start', async () => {
   return await xcOpenCodeWebService.start();
 });