Create a lock screen theme according to the following mockup and specification:
https://share.kde.org/index.php/s/0WRG8Us8qElwgDP
Thumbnail Animation: https://share.kde.org/index.php/s/DR1HV3d9HRHRigJ
The locks screen has to share the basic concept of the SDDM screen as it is in
practice, from the users perspective, almost the same thing.
Thats why it inherits the stock-blue background (editable from the lockscreen
settings).
When the lockscreen is actvated it displays a swift fade-to-black from desktop
and an even quicker fade-FROM-black to lockscreen. The goal is to make a swift
switch and make it feel more like a secure door slamming than a slow fade.
If that feels too complex this late in the release cycle a temporary solution
is just a direct switch, ignoring all animations.