React + FastAPI 풀 마이그레이션 — Streamlit 제거

- backend/ — FastAPI + JWT + 모든 REST 엔드포인트
- frontend/ — Next.js 14 + Tailwind + 7페이지 (대시보드/트레이드/거래소/자동매매/설정/내정보/로그인)
- core_logic.py — 신호계산/알림 로직 분리 (기존 app_streamlit.py 에서 추출)
- users_db.py + bcrypt 인증, exchange_keys.py + Fernet 암호화
- trades_db.py — 진입/청산 lifecycle 추적, signal_events raw 로그
- settings_db.py — 모든 운영 파라미터 DB 영속 저장 (RSI/거래량/펀딩비 임계값 포함)
- docker-compose: frontend / backend / postgres + Traefik 라우팅
- assets/logo.svg — JUNGGOMOA 그라디언트 로고

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/auth.py

@@ -0,0 +1,47 @@
+"""JWT 인증."""
+import os
+from datetime import datetime, timedelta
+from typing import Optional
+from fastapi import HTTPException, status, Depends
+from fastapi.security import OAuth2PasswordBearer
+from jose import jwt, JWTError
+
+import users_db
+
+JWT_SECRET = os.environ.get("JWT_SECRET", "change-me-in-production-please")
+JWT_ALG = "HS256"
+JWT_EXP_HOURS = 24 * 7
+
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login", auto_error=False)
+
+
+def create_token(username: str, role: str) -> str:
+    payload = {
+        "sub": username,
+        "role": role,
+        "exp": datetime.utcnow() + timedelta(hours=JWT_EXP_HOURS),
+        "iat": datetime.utcnow(),
+    }
+    return jwt.encode(payload, JWT_SECRET, algorithm=JWT_ALG)
+
+
+def decode_token(token: str) -> Optional[dict]:
+    try:
+        return jwt.decode(token, JWT_SECRET, algorithms=[JWT_ALG])
+    except JWTError:
+        return None
+
+
+def require_user(token: Optional[str] = Depends(oauth2_scheme)) -> dict:
+    if not token:
+        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="not authenticated")
+    payload = decode_token(token)
+    if not payload:
+        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="invalid token")
+    return payload
+
+
+def require_admin(payload: dict = Depends(require_user)) -> dict:
+    if payload.get("role") != "admin":
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="admin only")
+    return payload