Add a localStorage-backed insert-menu toggle (default off) that surfaces the formatting toolbar outside focus mode, and redesign it as a lean inline row: ghost icon buttons grouped by thin dividers, a level-reflecting heading glyph (pilcrow / H1-H3), and the active command as the only filled control.
Also keep the editor focused when using the toolbar: command buttons preventDefault on mousedown, and the dropdown menus return focus to the editor on close.
Add a rich-text formatting toolbar as the focus-mode header when the
WYSIWYG editor is active: heading dropdown, bold/italic/code, lists, and
link, with a priority+overflow responsive layout and live active-state
highlighting. The toolbar is a self-contained component driven through a
new FormattingController surface routed via EditorContent.
Remove the now-redundant slash-command feature (/todo, /code, /link,
/table) and its "Type / for commands" hint, since the toolbar covers
those actions; the shared suggestion renderer stays for #tag.
