Insert blank line

I'd love to be able to insert a blank line between commands but right now if I hit `Enter` multiple times I get extra `>` symbols even if I use `Hide` and `Show`.

```
Output demo.gif

Set FontSize 32
Set Width 1200
Set Height 600

Type "echo 'First!'"

Sleep 500ms

Enter

Hide
Enter
Show

Type "echo 'Second!'"

Sleep 500ms

Enter

Sleep 5s
```


Start by reproducing the shown VHS command sequence, especially repeated Enter commands with Hide and Show, and observe the generated terminal output or GIF. Trace the CLI's command handling for blank lines and verify the change by confirming that multiple Enter presses create visual blank lines without extra prompt symbols.

Written by the indexing model from the issue text.