Add FastAPI backend with agent system

backend/app/models/user.py

@@ -0,0 +1,15 @@
+from sqlalchemy import Column, String, Boolean, JSON
+from app.models.base import BaseModel
+
+
+class User(BaseModel):
+    __tablename__ = "users"
+
+    email = Column(String(255), unique=True, nullable=False, index=True)
+    hashed_password = Column(String(255), nullable=False)
+    full_name = Column(String(255), nullable=True)
+    is_active = Column(Boolean, default=True, nullable=False)
+    is_superuser = Column(Boolean, default=False, nullable=False)
+    # 用户级配置
+    llm_config = Column(JSON, nullable=True)  # LLM 模型配置
+    scheduler_config = Column(JSON, nullable=True)  # 定时任务配置