App-less system tasks (verify, regen, …) resolved to an empty displayName
and null icon in _taskNotificationDescriptor, so their completion toast
rendered an empty <strong></strong><br> — a blank bold line that showed as
a random gap above the message — and had no icon, unlike every other
notification. Treat any task with no app slug as a system task so it gets
the 'LibrePortal' subject and libreportal.svg icon.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: librelad <librelad@digitalangels.vip>
c7484572df