사용자 활성 세션 조회·종료 API 추가

userfront/lib/core/services/auth_proxy_service.dart

@@ -241,6 +241,29 @@ class AuthProxyService {
     }
   }
 
+  static Future<void> revokeSession(String sessionId) async {
+    final url = Uri.parse('$_baseUrl/api/v1/user/sessions/$sessionId');
+    final useCookie = AuthTokenStore.usesCookie();
+    final token = AuthTokenStore.getToken();
+    final client = createHttpClient(withCredentials: useCookie);
+    try {
+      final headers = <String, String>{'Content-Type': 'application/json'};
+      if (!useCookie && token != null && token.isNotEmpty) {
+        headers['Authorization'] = 'Bearer $token';
+      }
+      final response = await client.delete(url, headers: headers);
+      if (response.statusCode != 200) {
+        throw _error(
+          'err.userfront.dashboard.sessions.revoke',
+          '세션 종료에 실패했습니다: {{error}}',
+          detail: response.body,
+        );
+      }
+    } finally {
+      client.close();
+    }
+  }
+
   static Future<Map<String, dynamic>> verifyLoginShortCode(
     String shortCode, {
     bool verifyOnly = false,