✨ macOS 26 Tahoe App Icon

### Description

As of macOS 26 Tahoe, app icons are supposed to be [closed squares, which will then be clipped by the system](https://developer.apple.com/design/human-interface-guidelines/app-icons#:~:text=In%20iOS%2C%20iPadOS%2C%20and%20macOS%2C%20icons%20are%20square%2C%20and%20the%20system%20applies%20masking%20to%20produce%20rounded%20corners%20that%20precisely%20match%20the%20curvature%20of%20other%20rounded%20interface%20elements%20throughout%20the%20system%20and%20the%20bezel%20of%20the%20physical%20device%20itself.).

Opinions aside, CodeEdit looks really ugly in Squircle Jail.

Since CodeEdit's app icon is very similar to the icon used in Xcode 16, updating it for the upcoming design using inspiration from the new Xcode app icon would make sense.

### Alternatives Considered

_No response_

### Additional Context

_No response_

### Screenshots

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未指定具体文件或测试；首先定位 CodeEdit 的应用图标资源，以及将其打包用于 macOS 的配置。将当前图标与链接的 Apple 指南和 issue 截图进行比较，然后确认替换图标采用封闭方形设计，并符合预期的 Xcode 风格方向。

由索引模型根据 Issue 内容生成。