fix(audio): reap owned server on client shutdown

[Origamii520]

Replacement for #7 after rebasing the focused feature onto the rewritten current main history, as requested by the maintainer.

This change always stops and reaps the client-owned audio device server during application shutdown, closes its log handle, preserves externally owned servers, and still performs server cleanup if reverse-bridge shutdown raises.

Validation:

• 40 repository Python unittest cases passed in the existing project environment
• 4 focused audio lifecycle behavior checks passed
• commit authorship check passed
• git diff --check passed

No frontend files changed, so the frontend bundle is unchanged. Maintainers retain branch modification permission.

[Origamii520]

已按你的说明基于重写后的当前 main 重新提交，且只保留原 #7 的单一功能改动；本地测试与身份检查均已通过。烦请 @enkerewpo 审核。

[Origamii520]

补充：两个工作流当前均为 action_required，尚未创建任何 job，需要仓库维护者先批准该 fork PR 的 Actions 运行；本地验证与提交身份检查已完成。烦请 @enkerewpo 一并批准 CI 后审核。

[enkerewpo]

LGTM