feat: 과목 제한 해제 — 수학 외 자유 과목 추가 가능

- backend: ALLOWED_SUBJECT_NAMES, @IsIn() 삭제, 모든 서비스에서 name:'수학' 필터 제거
- frontend: purgeNonMath 제거 (대시보드 안정화), 과목 생성 가드 삭제
- defaultSubjectColor에 영어/국어/과학/사회/한국사 색상 추가

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

backend/src/dashboard/dashboard.service.ts

@@ -28,7 +28,6 @@ export class DashboardService {
           scheduledAt: { lte: now },
           studyLog: {
             psProblemId: null,
-            subject: { name: '수학' },
           },
         },
       }),
@@ -39,7 +38,6 @@ export class DashboardService {
           scheduledAt: { gt: now, lte: todayEnd },
           studyLog: {
             psProblemId: null,
-            subject: { name: '수학' },
           },
         },
       }),
@@ -47,7 +45,6 @@ export class DashboardService {
         where: {
           userId,
           psProblemId: null,
-          subject: { name: '수학' },
         },
         orderBy: { studiedAt: 'desc' },
         take: 5,
@@ -61,7 +58,6 @@ export class DashboardService {
         where: {
           userId,
           psProblemId: null,
-          subject: { name: '수학' },
           studiedAt: { gte: weekStart },
         },
         _count: { result: true },
@@ -70,7 +66,6 @@ export class DashboardService {
         where: {
           userId,
           tagId: { not: null },
-          tag: { subject: { name: '수학' } },
         },
         include: {
           tag: {

backend/src/me/me.controller.ts

@@ -16,7 +16,6 @@ import {
   IsArray,
   IsBoolean,
   IsEnum,
-  IsIn,
   IsInt,
   IsOptional,
   IsString,
@@ -34,7 +33,6 @@ import { AuthUser } from '../auth/jwt.strategy';
 import { MeService } from './me.service';
 
 const ALLOWED_AVATAR_MIME_TYPES = ['image/jpeg', 'image/png', 'image/webp'] as const;
-const ALLOWED_FOCUS_SUBJECTS = ['수학'] as const;
 const AVATAR_UPLOAD_DIR = join(__dirname, '..', '..', 'uploads', 'avatars');
 
 function ensureAvatarUploadDir() {
@@ -69,8 +67,8 @@ class OnboardingDto {
 
   @IsOptional()
   @IsArray()
-  @ArrayMaxSize(1)
-  @IsIn(ALLOWED_FOCUS_SUBJECTS, { each: true })
+  @ArrayMaxSize(5)
+  @IsString({ each: true })
   focusSubjects?: string[];
 
   @IsEnum(ReviewIntensity)
@@ -121,8 +119,8 @@ class ProfilePatchDto {
   @IsOptional()
   @IsArray()
   @ArrayMinSize(1)
-  @ArrayMaxSize(1)
-  @IsIn(ALLOWED_FOCUS_SUBJECTS, { each: true })
+  @ArrayMaxSize(5)
+  @IsString({ each: true })
   focusSubjects?: string[];
 
   @IsOptional()

backend/src/reviews/reviews.service.ts

@@ -37,7 +37,6 @@ export class ReviewsService {
         scheduledAt: { lte: soon },
         studyLog: {
           psProblemId: null,
-          subject: { name: '수학' },
         },
       },
       include: {
@@ -81,7 +80,6 @@ export class ReviewsService {
         scheduledAt: { lt: utcTodayStartKST },
         studyLog: {
           psProblemId: null,
-          subject: { name: '수학' },
         },
       },
       select: { id: true },
@@ -302,7 +300,6 @@ export class ReviewsService {
         status: { in: [ReviewStatus.done, ReviewStatus.skipped] },
         studyLog: {
           psProblemId: null,
-          subject: { name: '수학' },
         },
       },
       include: {
@@ -332,7 +329,6 @@ export class ReviewsService {
         scheduledAt: { gte: start, lt: end },
         studyLog: {
           psProblemId: null,
-          subject: { name: '수학' },
         },
       },
       select: {
@@ -379,7 +375,6 @@ export class ReviewsService {
         scheduledAt: { gte: start, lt: end },
         studyLog: {
           psProblemId: null,
-          subject: { name: '수학' },
         },
       },
       include: {

backend/src/stats/stats.service.ts

@@ -193,9 +193,8 @@ export class StatsService {
   }
 
   async bySubject(userId: number) {
-    // 프로토타입: 수학 과목만 노출 (soft filter — DB 데이터는 유지)
     const subjects = await this.prisma.subject.findMany({
-      where: { userId, name: '수학' },
+      where: { userId },
       include: {
         tags: {
           include: {

backend/src/study-logs/study-logs.service.ts

@@ -508,7 +508,6 @@ export class StudyLogsService {
       where: {
         userId,
         psProblemId: null,
-        subject: { name: '수학' },
         ...(opts.subjectId && { subjectId: opts.subjectId }),
         ...(opts.tagId && { tagId: opts.tagId }),
       },
@@ -803,6 +802,11 @@ function clamp01(n: number): number {
 function defaultSubjectColor(subjectName: string): string {
   const colorMap: Record<string, string> = {
     수학: "#3b82f6",
+    영어: "#10b981",
+    국어: "#f59e0b",
+    과학: "#8b5cf6",
+    사회: "#ec4899",
+    한국사: "#ef4444",
   };
 
   return colorMap[subjectName] ?? "#6366f1";

backend/src/subjects/subjects.controller.ts

@@ -9,20 +9,16 @@ import {
   Post,
   UseGuards,
 } from '@nestjs/common';
-import { IsIn, IsOptional, IsString, MaxLength, MinLength } from 'class-validator';
+import { IsOptional, IsString, MaxLength, MinLength } from 'class-validator';
 import { JwtAuthGuard } from '../auth/jwt-auth.guard';
 import { CurrentUser } from '../auth/current-user.decorator';
 import { AuthUser } from '../auth/jwt.strategy';
 import { SubjectsService } from './subjects.service';
 
-// 프로토타입: 수학만 허용 — 나중에 sed 한 방으로 해제 가능
-const ALLOWED_SUBJECT_NAMES = ['수학'] as const;
-
 class CreateSubjectDto {
   @IsString()
   @MinLength(1)
   @MaxLength(40)
-  @IsIn(ALLOWED_SUBJECT_NAMES)
   name: string;
 
   @IsOptional()
@@ -35,7 +31,6 @@ class UpdateSubjectDto {
   @IsString()
   @MinLength(1)
   @MaxLength(40)
-  @IsIn(ALLOWED_SUBJECT_NAMES)
   name?: string;
 
   @IsOptional()

backend/src/subjects/subjects.service.ts

@@ -6,18 +6,16 @@ export class SubjectsService {
   constructor(private readonly prisma: PrismaService) {}
 
   list(userId: number) {
-    // 프로토타입: 수학 과목만 노출 (soft filter — DB 데이터는 유지)
     return this.prisma.subject.findMany({
-      where: { userId, name: '수학' },
+      where: { userId },
       include: { tags: { orderBy: { name: 'asc' } } },
       orderBy: { createdAt: 'asc' },
     });
   }
 
   async getOne(userId: number, id: number) {
-    // 프로토타입: 수학 과목만 노출 (soft filter — DB 데이터는 유지)
     const subject = await this.prisma.subject.findFirst({
-      where: { id, userId, name: '수학' },
+      where: { id, userId },
       include: { tags: { orderBy: { name: 'asc' } } },
     });
     if (!subject) throw new NotFoundException();

frontend/src/app/dashboard/page.tsx

@@ -95,14 +95,6 @@ function DashboardBody() {
     setCoachDismissed(window.localStorage.getItem(COACH_DISMISS_KEY) === '1');
   }, []);
 
-  useEffect(() => {
-    const purged = localStorage.getItem('reloop-purged-non-math');
-    if (!purged) {
-      api.post('/study-logs/purge-non-math').then(() => {
-        localStorage.setItem('reloop-purged-non-math', 'true');
-      }).catch(() => {});
-    }
-  }, []);
 
   useEffect(() => {
     let cancelled = false;

frontend/src/app/onboarding/page.tsx

@@ -182,7 +182,7 @@ function OnboardingBody() {
       nickname: trimmedNickname,
       persona,
       reviewIntensity: DEFAULT_REVIEW_INTENSITY,
-      focusSubjects: goalType === 'none' ? [] : ['수학'],
+      focusSubjects: goalType === 'math-suneung' ? ['수학'] : [],
       focusUnits: goalType === 'math-suneung' ? focusUnits : [],
       onboarded: true,
     };

frontend/src/app/subjects/page.tsx

@@ -180,12 +180,6 @@ function SubjectsBody() {
       setSubjectModalError('과목 이름을 입력해 주세요.');
       return;
     }
-    // 프로토타입: 수학 단일 과목 잠금 — 추후 sed 한 방으로 해제
-    if (name !== '수학') {
-      setSubjectModalError('현재는 수학 과목만 추가할 수 있어요.');
-      return;
-    }
-
     setSubjectModalSaving(true);
     setSubjectModalError(null);