fix: hang task items past box

Prettier aligns the lines of a task item's first paragraph after its
`[ ] ` box. The box is now part of the item marker, so wrapping also
counts it on the first line only.

Prettier aligns HTML blocks in a task item the same way, but only from
their second line, and it adds the indent again on every pass. That
part is left out so a second pass changes nothing.