chore: initialize medical consultation agent demo

backend/app/models/department.py

@@ -0,0 +1,22 @@
+from __future__ import annotations
+
+from sqlalchemy import Boolean, ForeignKey, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.db.base import Base
+from app.models.mixins import TimestampMixin
+
+
+class Department(TimestampMixin, Base):
+    """科室模型：维护病例、知识库和评分规则的科室分类。"""
+
+    __tablename__ = "departments"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    name: Mapped[str] = mapped_column(String(100), nullable=False)
+    code: Mapped[str] = mapped_column(String(50), nullable=False, unique=True, index=True)
+    parent_id: Mapped[int | None] = mapped_column(ForeignKey("departments.id"), nullable=True)
+    sort_order: Mapped[int] = mapped_column(Integer, default=0)
+    is_active: Mapped[bool] = mapped_column(Boolean, default=True)
+
+    parent: Mapped["Department | None"] = relationship(remote_side=[id])