chore: complete OOTB QA audit

Fixes identified during the thorough distro review:
- Restore automatic wallpaper switching by removing image filters from deployed themes.
- Fix broken 'Style' menu entries by creating missing about.txt and screensaver.txt branding files.
- Clean up conflicting keybindings by removing deprecated tiling.conf and updating doc generator.
- Remove legacy Nord theme hack from nomarchy-theme-set.
- Fix JSON parse error in summer-day waybar theme.

themes/engine/scripts/nomarchy-theme-set

@@ -29,7 +29,7 @@ fi
 mkdir -p "$STATE_DIR"
 [[ ! -f $STATE_FILE ]] && echo "{}" > "$STATE_FILE"
 
-if [ ! -d "$THEMES_DIR/$THEME_NAME" ] && ! [[ "$THEME_NAME" == "nord" ]]; then
+if [ ! -d "$THEMES_DIR/$THEME_NAME" ]; then
   echo "Theme '$THEME_NAME' not found in $THEMES_DIR"
 fi