✨ Display progress bar or loading indicator in Open Quickly

### Description

After opening a large monorepo, I thought the Open Quickly feature was broken because it took several seconds to perform a search, and there was no indication that a search was being performed in the background.

### Alternatives Considered

_No response_

### Additional Context

_No response_

### Screenshots

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首先定位 CodeEdit macOS 应用中的 Open Quickly 搜索流程，并跟踪后台搜索的启动方式。在搜索运行期间添加一个可见的进度或加载指示器，并验证它会在慢速搜索期间显示，并在结果准备就绪时停止。

由索引模型根据 Issue 内容生成。