feat: 添加goRouter

lib/com/xiaoyan/main/LoginPage.dart

@@ -0,0 +1,13 @@
+import 'package:flutter/material.dart';
+
+class LoginPage extends StatelessWidget {
+  const LoginPage({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: Text('Login')),
+      body: Center(child: Text('Login Page')),
+    );
+  }
+}