fix(aiocqhttp): correct listener lifecycle handling

[StevenQinDev]

概述 / Overview

修复 aiocqhttp 适配器中三个关联的监听器生命周期问题：

• 每个 adapter 只注册一个 WebSocket connection observer，避免 RuntimeBot 初始化时产生三个重复 subscriber。
• 修正连接事件去重逻辑，正确比较缓存事件和传入事件。
• 保存 aiocqhttp 内部 message wrapper，使 unregister_listener() 能移除实际订阅的 callback，而不是抛出 NotImplementedError。
• 增加回归测试，覆盖 subscriber 数量、精确连接去重和 listener 注销。

Fixes three related listener-lifecycle issues in the aiocqhttp adapter:

• Register one WebSocket connection observer per adapter instance.
• Compare cached connection events against the incoming event.
• Retain internal message wrappers so unregister_listener() removes the actual aiocqhttp callback.
• Add regression tests for subscriber count, exact connection deduplication, and listener removal.

更改前后对比截图 / Screenshots

修改前 / Before:

修改后 / After:

检查清单 / Checklist

PR 作者完成 / For PR author

• 阅读仓库贡献指引了吗？ / Have you read the contribution guide?
• 我已签署或将在机器人提示后签署 CLA。 / I have signed, or will sign when prompted by the bot, the CLA.
• 与项目所有者沟通过了吗？ / Have you communicated with the project maintainer?
• 我确定已自行测试所作的更改，确保功能符合预期。 / I have tested the changes and ensured they work as expected.

项目维护者完成 / For project maintainer

• 相关 issues 链接了吗？ / Have you linked the related issues?
• 配置项写好了吗？迁移写好了吗？生效了吗？ / Have you written the configuration items? Have you written the migration? Has it taken effect?
• 依赖加到 pyproject.toml 和 core/bootutils/deps.py 了吗 / Have you added the dependencies to pyproject.toml and core/bootutils/deps.py?
• 文档编写了吗？ / Have you written the documentation?

验证 / Verification

• uv run pytest tests/unit_tests/platform/test_aiocqhttp_message_converter.py -q (23 passed)
• uv run pre-commit run --files src/langbot/pkg/platform/sources/aiocqhttp.py tests/unit_tests/platform/test_aiocqhttp_message_converter.py
• git diff --check

[RockChinQ]

Thanks for your contribution. Please use the PR template to file the PR, and attach the screenshot that proves your code works well.

[codecov]

Codecov Report

❌ Patch coverage is 82.35294% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/langbot/pkg/platform/sources/aiocqhttp.py	82.35%	3 Missing ⚠️

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