定期清理过期会话，评估并保存有价值信息，自动清理无价值会话。
Initial release of session-cleanup skill. - Periodically scans session directories, detects expired sessions, and evaluates their value. - Saves valuable sessions based on keyword matching; automatically deletes sessions deemed irrelevant. - Supports multiple session sources: cron runs, delivery queue, Telegram, and subagents, each with customized expiration rules. - Generates a cleanup report after each run. - Can be run manually or scheduled weekly with cron.