feat: [Feature Request] 重要记忆自动保鲜 — 防止高价值旧记忆因时间衰减丢失

[ethansecciond]

Pre-submission checklist | 提交前检查

• I have searched existing issues and this hasn't been mentioned before | 我已搜索现有问题，确认此问题尚未被提及
• I have read the project documentation and confirmed this issue doesn't already exist | 我已阅读项目文档并确认此问题尚未存在
• This issue is specific to MemOS and not a general software issue | 该问题是针对 MemOS 的，而不是一般软件问题

Problem Statement | 问题陈述

memos 能自动识别高价值的旧记忆，定期刷新时间戳或提升权重，防止因时间衰减导致重要信息丢失。
重要记忆自动保鲜机制

Willingness to Implement | 实现意愿

• I'm willing to implement this myself | 我愿意自己解决
• I would like someone else to implement this | 我希望其他人来解决