✨ (#298) 학생용 참여중인 클래스 조회 endTime 검증 필터 추가

Author: sunninz

backend/src/main/java/org/example/backend/domain/studentClass/service/StudentClassServiceImpl.java

@@ -132,6 +132,7 @@ public List<ClassroomResponseStudentDTO> getClassroomByStudentId() {
         List<Classroom> classrooms = classroomRepository.findAllById(classIds);
 
         return classrooms.stream()
+                .filter(classroom -> classroom.getEndDate().isAfter(LocalDate.now()))
                 .map(classroomConverter::toResponseStudentDTO)
                 .collect(Collectors.toList());
     }