Using tab during file autocomplete adds space

### Describe the bug

Using tab during file autocomplete via '@' adds the selected file/folder along with a space at the end. The space at the end causes to exit out of the autocomplete view, making the user to backspace to continue autocomplete. This makes tab and enter virtually the same, which is not ideal.

### Affected version

1.0.14

### Steps to reproduce the behavior

1. start copilot
2. enter @
3. select a folder
4. hit tab

### Expected behavior

tab should enter the selected folder, without the space at the end. should not exit out of autocomplete view

### Additional context

_No response_