🐛 fix: OAuth 인증 성공 시 redirect 경로 지정

Author: jiwon1217

backend/src/main/java/io/f1/backend/domain/user/app/handler/OAuthSuccessHandler.java

@@ -20,8 +20,6 @@
 @RequiredArgsConstructor
 public class OAuthSuccessHandler extends SimpleUrlAuthenticationSuccessHandler {
 
-    private final ObjectMapper objectMapper;
-
     @Override
     public void onAuthenticationSuccess(
             HttpServletRequest request, HttpServletResponse response, Authentication authentication)
@@ -30,13 +28,9 @@ public void onAuthenticationSuccess(
         response.setContentType("application/json;charset=UTF-8");
 
         if (principal.getUserNickname() == null) {
-            // 닉네임 설정 필요 → 202 Accepted
-            response.setStatus(HttpServletResponse.SC_ACCEPTED);
-            objectMapper.writeValue(response.getWriter(), Map.of("message", "닉네임을 설정하세요."));
+            response.sendRedirect("/signup");
         } else {
-            // 정상 로그인 → 200 OK
-            response.setStatus(HttpServletResponse.SC_OK);
-            objectMapper.writeValue(response.getWriter(), Map.of("message", "로그인 성공"));
+            response.sendRedirect("/room");
         }
     }
 }