`_apply_note_items` didn't ignore items on a non-list note — it deleted them.
That was survivable only because nothing in the product could produce a note
holding both a body and items.
M13 makes exactly that the normal shape: a checklist is something a note HAS,
not something a note IS. Against that shape this guard is a data-loss path — the
first sync after adding a checklist to a note would wipe it.
Landing it before the UI that can create the state, so there is never a window
where the two disagree. `kind` itself, and the rest of the merge, follow.
bvandeusen
229076c82d