🐞 Command-A (Copy All) is capturing, but not highlighting

### Description

File with 19 lines of text - when trying to capture all via the Command-A key sequence, only the first 18 lines are highlighted. However, after copying via Command-C and pasting via Command-V, all of the lines are pasted. So all the lines are being selected, but not all the lines are highlighted.

### To Reproduce

1. Open any existing file or create a new file
2. Enter a few lines
3. Press Command+A to attempt to highlight all text
4. Press Command+C to copy the text

### Expected Behavior

Pressing Command-A should highlight all text in the open editor window

### Version Information

CodeEdit: [e.g. 0.0.x-alpha.y]
macOS: [e.g. 13.2.1]
Xcode: [e.g. 14.2]

### Additional Context

_No response_

### Screenshots

首先，在包含多行文件的 CodeEditTextView 编辑器中复现 Command-A，然后检查最后一行附近的选择和高亮行为。完成的标准是：按下 Command-A 后每一行都能被明显高亮，同时 Command-C 和 Command-V 仍然包含完整文本。

由索引模型根据 Issue 内容生成。