✨ [Feature]: Tree-menu search box placeholder supports customization

[falcon-jin]

What problem does this feature solve

What does the proposed API look like

希望tree-menu 搜索框placeholder支持自定义

[Issues-translate-bot]

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Title: ✨ [Feature]: tree-menu search box placeholder supports customization

[Huangyilin19]

好的，我们内部先评审下解决方案。

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

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Okay, let’s review the solution internally first.