Implement a toolbar for quick, easy access to formatting options

For bold, italic and strikethrough we either apply the formatting to the selection if it exists or insert a helper text

Same for headings, but on top of that we cycle between three levels of heading when the button is clicked consecutively. The whole heading doesn't need to be selected for that

Lists and ordered lists will toggle the itemization. Checklists will toggle the completion of the task.

Codeblocks will apply inline markup based on context

Weblinks will use the selection for the uri or the uri description field when possible.