Add Redis-based one-time download token support

Integrate Redis as a backend for one-time download token validation, with in-memory fallback. Added RedisManager for connection lifecycle, TokenStore for atomic token usage checks, and related configuration via environment variables. Updated download flow to ensure tokens are single-use, and improved API robustness for batch operations. Updated dependencies to include redis and cachetools.

utils/conf/appmeta.py

@@ -11,14 +11,36 @@ description = 'DiskNext Server 是一款基于 FastAPI 的网盘系统，支持
 license_info = {"name": "GPLv3", "url": "https://opensource.org/license/gpl-3.0"}
 
 BackendVersion = "0.0.1"
+"""后端版本"""
 
 IsPro = False
 
 mode: str = os.getenv('MODE', 'master')
+"""运行模式"""
 
 debug: bool = os.getenv("DEBUG", "false").lower() in ("true", "1", "yes") or False
+"""是否启用调试模式"""
 
 if debug:
     log.warning("Debug mode is enabled. This is not recommended for production use.")
 
-database_url: str = os.getenv("DATABASE_URL", "sqlite+aiosqlite:///disknext.db")
+database_url: str = os.getenv("DATABASE_URL", "sqlite+aiosqlite:///disknext.db")
+"""数据库地址"""
+
+redis_url: str | None = os.getenv("REDIS_URL")
+"""Redis 主机地址"""
+
+_redis_port = os.getenv("REDIS_PORT")
+redis_port: int = int(_redis_port) if _redis_port else 6379
+"""Redis 端口，默认 6379"""
+
+redis_password: str | None = os.getenv("REDIS_PASSWORD")
+"""Redis 密码"""
+
+_redis_db = os.getenv("REDIS_DB")
+redis_db: int = int(_redis_db) if _redis_db else 0
+"""Redis 数据库索引，默认 0"""
+
+_redis_protocol = os.getenv("REDIS_PROTOCOL")
+redis_protocol: int = int(_redis_protocol) if _redis_protocol else 3
+"""Redis 协议版本，默认 3"""