Make mappings repeatable with `.`

### 🚀 The feature, motivation and pitch

Tired of checking off all the checkboxes with `ch`? Just want to repeat the last checkoff action?

Let's make mappings repeatable with the `.`. Now you check off one box with the normal mapping and can use `.` to check of more boxes.

### Alternatives

_No response_

### Additional context

_No response_

The issue names no files, tests, or entry points. Start by locating the existing checkbox mapping and the plugin's handling of repeatable Neovim mappings, then verify that the normal checkoff action can be repeated with `.` across multiple boxes.

Written by the indexing model from the issue text.