prepare fastapi root layout for server deployment

app/models/department.py

@@ -0,0 +1,22 @@
+from __future__ import annotations
+
+from sqlalchemy import BigInteger, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db.base import Base
+from app.models.mixins import TimestampMixin
+
+BIGINT_PK = BigInteger().with_variant(Integer, "sqlite")
+
+
+class Department(TimestampMixin, Base):
+    """科室模型：使用用户端确定的 department 表字段。"""
+
+    __tablename__ = "department"
+
+    id: Mapped[int] = mapped_column(BIGINT_PK, primary_key=True, autoincrement=True, comment="科室ID")
+    name: Mapped[str] = mapped_column(String(100), nullable=False, comment="科室名称")
+    category: Mapped[str] = mapped_column(String(50), nullable=False, comment="科室分类")
+    institution_id: Mapped[int] = mapped_column(BigInteger, nullable=False, index=True, comment="所属机构ID")
+
+    __table_args__ = {"comment": "科室表"}