update background logic

backgrounds saved for light/dark modes are now stored as the absolute
path, so config keys chore.bg_dark and chore.bg_light now contain the
string of absolute path to image files.

in addition to this update, swww_single chore now copies the current
background image to the location of chore.current_bg, which can be used
to directly access the image of the current background.

utility/nemo/set_wallpaper.sh

@@ -6,13 +6,10 @@
 # cp utility/nemo/set_wallpaper.sh ~/.local/share/nemo/scripts
 # chmod +x ~/.local/share/nemo/scripts/set_wallpaper.sh
 
+# shellcheck source=../../_reve.sh
 source "$(reve where)/_reve"
-reve_folder="$HOME/.config/reve"
-reve_desktop_mode="$reve_folder/desktop_mode"
 
-mode=$(util_readf "$reve_desktop_mode")
-bgl="$reve_folder/chore/bg_light"
-bgd="$reve_folder/chore/bg_dark"
+mode=$(util_read_config base.desktop_mode)
 
 if [ "$NEMO_SCRIPT_SELECTED_FILE_PATHS" = "" ]; then
   first=$1
@@ -20,10 +17,5 @@ else
   first=$(echo "$NEMO_SCRIPT_SELECTED_FILE_PATHS" | head -n 1)
 fi
 
-if [ "$mode" = "dark" ]; then
-  cp -T "$first" "$bgd"
-else
-  cp -T "$first" "$bgl"
-fi
-
-reload mode/swww_single $mode
+util_write_config "chore.bg_$mode" "$first"
+reload mode/swww_single "$mode"