fix: 扫码登录成功后返回空页面并自动关闭

手机端扫码成功后直接关闭并返回飞书，不显示任何页面内容。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/controller/AuthController.php

@@ -261,49 +261,22 @@ class AuthController extends BaseController
             $session->user_id = $user->id;
             $session->save();
 
-            // 返回简单页面，让用户知道可以关闭了
-            return new \Webman\Http\Response(200, [], '<!DOCTYPE html>
+            // 返回空页面，自动关闭（飞书APP内会自动返回）
+            return new \Webman\Http\Response(200, ['Content-Type' => 'text/html; charset=utf-8'], '<!DOCTYPE html>
 <html>
 <head>
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <title>登录成功</title>
-    <style>
-        body {
-            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
-            display: flex;
-            align-items: center;
-            justify-content: center;
-            min-height: 100vh;
-            margin: 0;
-            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
-            color: #fff;
-            text-align: center;
-        }
-        .container {
-            padding: 40px 20px;
-        }
-        h1 {
-            margin: 0 0 10px 0;
-            font-size: 28px;
-        }
-        p {
-            margin: 10px 0 0 0;
-            font-size: 16px;
-            opacity: 0.9;
-        }
-        .icon {
-            font-size: 64px;
-            margin-bottom: 20px;
-        }
-    </style>
+    <script>
+        // 尝试关闭窗口（飞书APP内会自动返回）
+        window.close();
+        // 备用：如果无法关闭，显示简单提示
+        setTimeout(function() {
+            document.body.innerHTML = "<div style=\'display:flex;align-items:center;justify-content:center;min-height:100vh;margin:0;font-family:sans-serif;text-align:center;color:#666;\'><p>登录成功<br>您可以关闭此页面</p></div>";
+        }, 100);
+    </script>
 </head>
 <body>
-    <div class="container">
-        <div class="icon">✅</div>
-        <h1>登录成功</h1>
-        <p>您可以关闭此页面返回电脑端继续操作</p>
-    </div>
 </body>
 </html>');
         } catch (\Exception $e) {