refactor: remove backup files

backend/models/database.py.backup

@@ -1,56 +0,0 @@
-from sqlalchemy import create_engine
-from sqlalchemy.ext.declarative import declarative_base
-from sqlalchemy.orm import sessionmaker
-from datetime import datetime, timezone
-from backend.config import settings
-import sqlite3
-
-# SQLite 类型转换器：将从数据库读取的字符串转换为 timezone-aware datetime
-def convert_timestamp(val):
-    """将从数据库读取的字符串转换为 timezone-aware datetime (UTC)"""
-    if val is None:
-        return None
-    # 解析 ISO 8601 格式的字符串
-    try:
-        dt = datetime.fromisoformat(val.decode() if isinstance(val, bytes) else val)
-        # 如果是 naive datetime，添加 UTC timezone
-        if dt.tzinfo is None:
-            dt = dt.replace(tzinfo=timezone.utc)
-        return dt
-    except (ValueError, AttributeError):
-        return None
-
-# 注册 SQLite 类型转换器（全局）
-sqlite3.register_converter("DATETIME", convert_timestamp)
-sqlite3.register_converter("TIMESTAMP", convert_timestamp)
-
-# 创建数据库引擎
-# 为 SQLite 连接添加 detect_types 参数以启用类型转换
-engine = create_engine(
-    settings.DATABASE_URL,
-    connect_args={
-        "check_same_thread": False,  # SQLite 特定配置
-        "detect_types": sqlite3.PARSE_DECLTYPES | sqlite3.PARSE_COLNAMES  # 启用类型转换
-    },
-    echo=False,  # 生产环境设为 False
-)
-
-# 创建会话工厂
-SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
-
-# 创建基类
-Base = declarative_base()
-
-
-def get_db():
-    """依赖注入：获取数据库会话"""
-    db = SessionLocal()
-    try:
-        yield db
-    finally:
-        db.close()
-
-
-def init_db():
-    """初始化数据库：创建所有表"""
-    Base.metadata.create_all(bind=engine)