fix: a desktop Plasma makes after the layout has run gets the classroom's wallpaper

Tiny Pebbles came through the 0.2.2 upgrade on Plasma's own purple
wallpaper: its desktop was containment 10, made after the layout had run
(most likely the television arriving after a night-time reboot), with no
wallpaper configured. The look and feel's fallback could not catch it,
because it named a file and Plasma only accepts a wallpaper package there.

The fallback is now the EkklesiaClassroom package, whose one image links to
the classroom's picture. classroom-desktop-wallpaper, run before every
plasmashell start, writes the picture into every desktop containment the
file already has: found by plugin, never by number; panels and everything
else byte for byte; a file that is already right not written at all.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

config/plasma/lookandfeel/contents/defaults

@@ -24,8 +24,18 @@ cursorTheme=breeze_cursors
 library=org.kde.breeze
 theme=Breeze
 
+# The picture a desktop gets when nothing has said which. That is every
+# desktop Plasma makes on its own after the layout has run: a television
+# switched on after the computer, a second screen, a new activity.
+#
+# A wallpaper PACKAGE NAME, not a file. Plasma's DefaultWallpaper looks it
+# up as wallpapers/<name> and nothing else. This line was a path until
+# 0.2.6.6, which Plasma cannot load as a package, so every such desktop
+# fell back to Plasma's own purple one — measured, and it is what Tiny
+# Pebbles showed after the 0.2.2 upgrade. The package is a directory whose
+# one image is a link to the classroom's file; see build-release.sh.
 [Wallpaper]
-Image=/usr/share/backgrounds/ekklesia/classroom-calm.png
+Image=EkklesiaClassroom
 
 [KSplash]
 Theme=None