wallpaper: one run() for Apply and the engine, with a finished signal

The engine's timer must set wallpapers the same way Apply does so the
burn plays. run() is that one path; applied stays Apply's alone (save bar,
window close) while finished marks every run's end, which is what the
spread overlay now hides on.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/desktop/modules/appearance/WallpaperSpread.qml b/desktop/modules/appearance/WallpaperSpread.qml
index c133343..d1c383d 100644
--- a/desktop/modules/appearance/WallpaperSpread.qml
+++ b/desktop/modules/appearance/WallpaperSpread.qml
@@ -59,9 +59,10 @@ Scope {
                     newImg.source = to;
                     win.running = true;
                 }
-                // A failed set may have left either picture underneath, so
-                // the cover goes at once rather than claiming the new one.
-                function onApplied(ok) {
+                // Any run's end, Apply's or the engine's. A failed set may
+                // have left either picture underneath, so the cover goes at
+                // once rather than claiming the new one.
+                function onFinished(ok) {
                     win.done = true;
                     if (!ok) win.running = false;
                     else if (!anim.running) win.running = false;