希望改进 macOS 端 desktop app 的图标

[LYitYI]

Problem
What real problem does this solve? Who hits it?
reasonix 的图标大出其他 app 一圈，显得格格不入并且有点不太美观

Proposed change
What you'd like reasonix to do differently. Include a sketch of the
UX or API if relevant.
将图标尺寸修改为 macOS 推荐的尺寸，与其他 app 保持一致

Alternatives considered
What else you tried or thought about. "I just want it" is not an
alternative.
暂无

Scope check

• This belongs in core reasonix (not better as a separate npm package)
• I've read CLAUDE.md and CONTRIBUTING.md