khtml was dropped from the Manjaro stable repo as of [Stable Update] 2024-05-18 - Linux-Firmware, PHP, Gitlab, Qt6 and is now only available in the AUR.
Either way, khtml now depends on kparts5.
calligra no longer depends on khtml.
It appears you haven’t updated in a number of months and may be in an unsupported, partial upgrade state. Make sure your mirrors are up to date and do not attempt to update AUR packages until after you’ve updated all repo packages and rebooted.