Render checkboxes

### Your use case

#### What would you like to do?

I'd like to have proper checkboxes in the app. Just like here on github.

- [ ] Test 1
- [x] Test 2

- they shall be checkable by at least the author.
- automatically add a new item when pressing enter for a new line

#### Why would you like to do it?

- it looks better
- it's cool to click on things
- it's useful because you don't need to manually edit a post to indicate that something is checked

#### How would you like to achieve it?

- I have no idea how to implement this

### Have you considered any alternatives?

_No response_

### Additional context

_No response_