Initial commit: clean project structure

- Backend: FastAPI + SQLAlchemy + Celery (Python 3.11+)
- Frontend: Vue 3 + TypeScript + Pinia + Tailwind
- Admin Frontend: separate Vue 3 app for management
- Docker Compose: 9 services orchestration
- Specs: design prototypes, memory system PRD, product roadmap

Cleanup performed:
- Removed temporary debug scripts from backend root
- Removed deprecated admin_app.py (embedded UI)
- Removed duplicate docs from admin-frontend
- Updated .gitignore for Vite cache and egg-info

backend/app/core/security.py

@@ -0,0 +1,25 @@
+from datetime import datetime, timedelta, timezone
+
+from jose import JWTError, jwt
+
+from app.core.config import settings
+
+ALGORITHM = "HS256"
+ACCESS_TOKEN_EXPIRE_DAYS = 7
+
+
+def create_access_token(data: dict) -> str:
+    """创建 JWT token"""
+    to_encode = data.copy()
+    expire = datetime.now(timezone.utc) + timedelta(days=ACCESS_TOKEN_EXPIRE_DAYS)
+    to_encode.update({"exp": expire})
+    return jwt.encode(to_encode, settings.secret_key, algorithm=ALGORITHM)
+
+
+def decode_access_token(token: str) -> dict | None:
+    """解码 JWT token"""
+    try:
+        payload = jwt.decode(token, settings.secret_key, algorithms=[ALGORITHM])
+        return payload
+    except JWTError:
+        return None