* feat: integrate MDXEditor for card description with markdown support
* feat: replace textarea with markdown editor for card descriptions and improve styling
* refactor: replace MDXEditor with Tiptap for rich text editing
* fix: prevent menu item from taking focus and submitting
* feat: replace editor menu with bubble menu and add placeholder text
* feat: implement slash commands menu in editor with suggestion API
* chore: update editor styling
* chore: update editor placeholder text
* fix: navigate command list by keyboard and tweak styling
* fix: prevent editor onBlur from submitting NewCardForm
---------
Co-authored-by: Henry <henry_ball@hotmail.co.uk>
