fix:修复项目结构

backend/app/models.py

@@ -0,0 +1,30 @@
+from datetime import datetime, timedelta
+
+from sqlalchemy import DateTime, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column, Session
+
+from app.database import Base
+
+
+class HTMLFile(Base):
+    __tablename__ = "html_files"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
+    unique_id: Mapped[str] = mapped_column(
+        String(32), unique=True, index=True, nullable=False
+    )
+    filename: Mapped[str] = mapped_column(String(255), nullable=False)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime, default=datetime.utcnow, nullable=False
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime, default=datetime.utcnow, onupdate=datetime.utcnow, nullable=False
+    )
+
+    @classmethod
+    def delete_expired_records(cls, db: Session, days: int = 5) -> int:
+        """删除超过指定天数的记录"""
+        cutoff_date = datetime.utcnow() - timedelta(days=days)
+        deleted = db.query(cls).filter(cls.created_at < cutoff_date).delete()
+        db.commit()
+        return deleted