[Bug]多会话/会话规则并发写入时，保存对话历史会触发 database is locked #6443

Error occurred while processing agent request: (sqlite3.OperationalError) database is locked
[SQL: UPDATE conversations SET updated_at=?, content=?, token_usage=? WHERE conversations.conversation_id = ?]

### Reproduce / 如何复现？

在 WebUI / WebChat 场景下，以下操作都比较容易触发：

新建会话后立刻发送第一条消息
在启用人格功能后，第一次对话就会触发，后续关闭人格并清空聊天记录，任然触发
停止当前回复后，紧接着切换会话或继续发送消息

### AstrBot version, deployment method (e.g., Windows Docker Desktop deployment), provider used, and messaging platform used. / AstrBot 版本、部署方式（如 Windows Docker Desktop 部署）、使用的提供商、使用的消息平台适配器

Linux操作系统Ubuntu-22.04-x64  使用docker部署，最开始使用宝塔面板应用商店安装，第一次出现该问题，后面改用docker直接拉取，任然出现 
Windows操作系统win11 同样使用docker部署，问题再次复现             
两个操作系统均测试使用onebot v11和官方文档中的QQsocket，触发期间napcat连接及日志均正常

### OS

Not sure

### Logs / 报错日志

```text
[2026-03-13 09:32:29.501] [Core] [ERRO] [v4.19.4] [utils.metrics:69]: 保存指标到数据库失败: (sqlite3.OperationalError) database is locked

[SQL: 

                    INSERT INTO platform_stats (timestamp, platform_id, platform_type, count)

                    VALUES (?, ?, ?, ?)

                    ON CONFLICT(timestamp, platform_id, platform_type) DO UPDATE SET

                        count = platform_stats.count + EXCLUDED.count

                    ]

[parameters: (datetime.datetime(2026, 3, 13, 9, 0), 'aiocqhttp', 'unknown', 1)]

(Background on this error at: https://sqlalche.me/e/20/e3q8)

[2026-03-13 09:32:29.508] [Core] [ERRO] [v4.19.4] [agent_sub_stages.internal:371]: Error occurred while processing agent: (sqlite3.OperationalError) database is locked

[SQL: UPDATE conversations SET updated_at=?, content=? WHERE conversations.conversation_id = ?]

[parameters: ('2026-03-13 09:32:24.433964', '[{"role": "user", "content": [{"type": "text", "text": "\\u4f60\\u662f\\u8c01"}, {"type": "text", "text": "<system_reminder>Current datetime: 2026-03 ... (51276 characters truncated) ... 6fe\\u670d\\u52a1\\u7684\\u90e8\\u7f72\\u5462\\uff1f\\u544a\\u8bc9\\u6211\\u4f60\\u7684\\u60f3\\u6cd5\\uff0c\\u6211\\u6765\\u914d\\u5408\\u4f60~"}]}]', 'e23ab3e2-5b9c-4784-80b5-813ecc1e1e6e')]

(Background on this error at: https://sqlalche.me/e/20/e3q8) 

这时对话会出现
Error occurred while processing agent request: (sqlite3.OperationalError) database is locked
[SQL: UPDATE conversations SET updated_at=?, content=?, token_usage=? WHERE conversations.conversation_id = ?]
[parameters: ('2026-03-16 10:33:29.878621', '[{"role": "user", "content": [{"type": "text", "text": "\\u4f60\\u597d"}, {"type": "text", "text": "<system_reminder>Current datetime: 2026-03-16 18: ... (376 characters truncated) ... ff0c\\u8fd8\\u662f\\u5176\\u4ed6\\u9700\\u8981\\u534f\\u52a9\\u7684\\u4e8b\\u60c5\\uff0c\\u6211\\u90fd\\u5f88\\u4e50\\u610f\\u5e2e\\u5fd9\\u3002"}]}]', 3382, '3835f073-a207-4ca4-87bd-7c1762e00163')]
(Background on this error at: https://sqlalche.me/e/20/e3q8)

### Are you willing to submit a PR? / 你愿意提交 PR 吗？

- [x] Yes!

### Code of Conduct

- [x] I have read and agree to abide by the project's [Code of Conduct](https://docs.github.com/zh/site-policy/github-terms/github-community-code-of-conduct)。