remove: 프로필 학년/등급 섹션 삭제

GradeCardCarousel, 현재등급/목표등급 배지, 관련 state/함수 모두 제거.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/app/profile/page.tsx

@@ -6,7 +6,6 @@ import { useRouter } from 'next/navigation';
 import styled, { css } from 'styled-components';
 import AppShell from '@/components/layout/AppShell';
 import { Icon } from '@/components/ui/Icon';
-import GradeCardCarousel from '@/components/ui/GradeCardCarousel';
 import { Button, Card } from '@/components/ui/primitives';
 import { useToast } from '@/components/ui/Toast';
 import {
@@ -103,8 +102,6 @@ function ProfileBody() {
   const [user, setUser] = useState<MeUser | null>(null);
   const [nicknameDraft, setNicknameDraft] = useState('');
   const [isEditingNickname, setIsEditingNickname] = useState(false);
-  const [currentGradeDraft, setCurrentGradeDraft] = useState(5);
-  const [targetGradeDraft, setTargetGradeDraft] = useState(3);
   const [notifications, setNotifications] =
     useState<NotificationPrefs>(DEFAULT_NOTIFICATIONS);
   const [studyLogs, setStudyLogs] = useState<StudyLog[]>([]);
@@ -115,19 +112,11 @@ function ProfileBody() {
 
   const userRef = useRef<MeUser | null>(null);
   const avatarFileInputRef = useRef<HTMLInputElement | null>(null);
-  const currentGradeRef = useRef(5);
-  const targetGradeRef = useRef(3);
-  const gradeSaveTimerRef = useRef<number | null>(null);
   const notificationsReadyRef = useRef(false);
 
   useEffect(() => {
     void loadProfile();
 
-    return () => {
-      if (gradeSaveTimerRef.current !== null) {
-        window.clearTimeout(gradeSaveTimerRef.current);
-      }
-    };
   }, []);
 
   useEffect(() => {
@@ -138,14 +127,6 @@ function ProfileBody() {
     };
   }, [avatarPreviewUrl]);
 
-  useEffect(() => {
-    currentGradeRef.current = currentGradeDraft;
-  }, [currentGradeDraft]);
-
-  useEffect(() => {
-    targetGradeRef.current = targetGradeDraft;
-  }, [targetGradeDraft]);
-
   useEffect(() => {
     if (typeof window === 'undefined') return;
 
@@ -188,9 +169,6 @@ function ProfileBody() {
       userRef.current = nextUser;
       setUser(nextUser);
       setNicknameDraft(nextUser.nickname);
-      setCurrentGradeDraft(nextUser.currentGrade ?? 5);
-      setTargetGradeDraft(nextUser.targetGrade ?? 3);
-
 
       setAvatarPreviewUrl(null);
       setStudyLogs(logs);
@@ -213,15 +191,11 @@ function ProfileBody() {
       userRef.current = nextUser;
       setUser(nextUser);
       setNicknameDraft(nextUser.nickname);
-      setCurrentGradeDraft(nextUser.currentGrade ?? currentGradeRef.current);
-      setTargetGradeDraft(nextUser.targetGrade ?? targetGradeRef.current);
 
       showToast({ message: successMessage, variant: 'success' });
     } catch {
       const currentUser = userRef.current;
       setNicknameDraft(currentUser?.nickname ?? '');
-      setCurrentGradeDraft(currentUser?.currentGrade ?? 5);
-      setTargetGradeDraft(currentUser?.targetGrade ?? 3);
       showToast({ message: '저장에 실패했습니다', variant: 'danger' });
     } finally {
       setSavingKey((current) => (current === key ? null : current));
@@ -266,33 +240,6 @@ function ProfileBody() {
     }
   }
 
-  function queueGradeSave() {
-    if (!userRef.current) return;
-
-    const nextCurrent = currentGradeRef.current;
-    const nextTarget = targetGradeRef.current;
-    const prevCurrent = userRef.current.currentGrade ?? 5;
-    const prevTarget = userRef.current.targetGrade ?? 3;
-
-    if (nextCurrent === prevCurrent && nextTarget === prevTarget) {
-      return;
-    }
-
-    if (gradeSaveTimerRef.current !== null) {
-      window.clearTimeout(gradeSaveTimerRef.current);
-    }
-
-    gradeSaveTimerRef.current = window.setTimeout(() => {
-      void patchProfile(
-        {
-          currentGrade: currentGradeRef.current,
-          targetGrade: targetGradeRef.current,
-        },
-        'grades',
-      );
-    }, 400);
-  }
-
   function handlePersonaSelect(value: Persona) {
     if (!user || value === user.persona) return;
     void patchProfile({ persona: value }, 'persona', '페르소나 변경됨 — 복습 스케줄을 새 설정에 맞게 재계산했어요');
@@ -546,39 +493,10 @@ function ProfileBody() {
                   <PlanBadge>{planLabel(user.subscriptionTier)}</PlanBadge>
                 </NameRow>
                 <Email>{user.email}</Email>
-                <BadgeRow>
-                  <InfoBadge>현재 등급 {currentGradeDraft}등급</InfoBadge>
-                  <InfoBadge>목표 등급 {targetGradeDraft}등급</InfoBadge>
-                </BadgeRow>
               </AccountContent>
             </AccountRow>
           </CardSection>
 
-          <CardSection>
-            <SectionHeader>
-              <SectionTitle>학년/등급</SectionTitle>
-            </SectionHeader>
-            <SliderGroup>
-              <GradeCardCarousel
-                label="현재 등급"
-                value={currentGradeDraft}
-                helper="현재 체감 실력 기준"
-                onChange={(value) => {
-                  setCurrentGradeDraft(value);
-                  window.requestAnimationFrame(queueGradeSave);
-                }}
-              />
-              <GradeCardCarousel
-                label="목표 등급"
-                value={targetGradeDraft}
-                helper="도달하고 싶은 다음 기준"
-                onChange={(value) => {
-                  setTargetGradeDraft(value);
-                  window.requestAnimationFrame(queueGradeSave);
-                }}
-              />
-            </SliderGroup>
-          </CardSection>
         </Grid>
       ) : null}
 
@@ -1075,25 +993,6 @@ const Email = styled.p`
   color: ${theme.color.textMute};
 `;
 
-const BadgeRow = styled.div`
-  display: flex;
-  gap: 10px;
-  flex-wrap: wrap;
-`;
-
-const InfoBadge = styled.div`
-  padding: 10px 12px;
-  border-radius: 14px;
-  background: rgba(255, 255, 255, 0.04);
-  border: 1px solid ${theme.color.borderSoftAlpha};
-  color: ${theme.color.textSub};
-  font-size: 13px;
-`;
-
-const SliderGroup = styled.div`
-  display: grid;
-  gap: 18px;
-`;
 
 const PersonaGrid = styled.div`
   display: grid;