feat(kde): Restore KDE Wallpaper Engine integration for KDE 6

Containerfile

@@ -472,6 +472,7 @@ RUN if grep -q "kinoite" <<< "${BASE_IMAGE_NAME}"; then \
             kf6-kio-gui && \
         rpm-ostree install \
             steamdeck-kde-presets-desktop \
+            wallpaper-engine-kde-plugin \
             kdeconnectd \
             kdeplasma-addons \
             rom-properties-kf6 \
@@ -481,8 +482,11 @@ RUN if grep -q "kinoite" <<< "${BASE_IMAGE_NAME}"; then \
         mkdir -p /tmp/kwin-system76-scheduler-integration && \
         curl -Lo /tmp/kwin-system76-scheduler-integration/archive.tar.gz https://github.com/maxiberta/kwin-system76-scheduler-integration/archive/refs/heads/main.tar.gz && \
         tar --no-same-owner --no-same-permissions --no-overwrite-dir --strip-components 1 -xvf /tmp/kwin-system76-scheduler-integration/archive.tar.gz -C /tmp/kwin-system76-scheduler-integration && \
+        git clone https://github.com/catsout/wallpaper-engine-kde-plugin.git --depth 1 --branch qt6 /tmp/wallpaper-engine-kde-plugin && \
         kpackagetool6 --type=KWin/Script --global --install /tmp/kwin-system76-scheduler-integration && \
+        kpackagetool6 --type=Plasma/Wallpaper --global --install /tmp/wallpaper-engine-kde-plugin/plugin && \
         rm -rf /tmp/kwin-system76-scheduler-integration && \
+        rm -rf /tmp/wallpaper-engine-kde-plugin && \
         sed -i '/<entry name="launchers" type="StringList">/,/<\/entry>/ s/<default>[^<]*<\/default>/<default>preferred:\/\/browser,applications:steam.desktop,applications:net.lutris.Lutris.desktop,applications:org.gnome.Ptyxis.desktop,applications:org.kde.discover.desktop,preferred:\/\/filemanager<\/default>/' /usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/config/main.xml && \
         sed -i '/<entry name="favorites" type="StringList">/,/<\/entry>/ s/<default>[^<]*<\/default>/<default>preferred:\/\/browser,steam.desktop,net.lutris.Lutris.desktop,systemsettings.desktop,org.kde.dolphin.desktop,org.kde.kate.desktop,org.gnome.Ptyxis.desktop,org.kde.discover.desktop,system-update.desktop<\/default>/' /usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/config/main.xml && \
         sed -i 's@\[Desktop Action new-window\]@\[Desktop Action new-window\]\nX-KDE-Shortcuts=Ctrl+Alt+T@g' /usr/share/applications/org.gnome.Ptyxis.desktop && \