New pin field type: Checkbox

As a user, I would like to be able to use a user-defined pin field of the "checkbox" type, with which I can check off individual points directly in the pin.

This allows simple yes/no statuses or completed test steps to be documented quickly and clearly - for example:

☐ Building status recorded

☑ Advance performance checked

The visual representation as a checkbox makes the status recognizable at a glance and improves traceability in the course of the project.