Fix blurry cPanel icon: 256x256 PNG + per-user sprite rebuild

Regenerated icon at 256x256 with transparency for crisp rendering.
Added cpapi2 Branding gensprites call for all cPanel users during
install so sprites update immediately.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/install.sh

@@ -124,6 +124,13 @@ if [[ -d "$CPANEL_BASE" ]]; then
     rm -rf "$PLUGIN_TMPDIR"
     # Rebuild icon sprites so the new icon appears in cPanel
     /usr/local/cpanel/bin/rebuild_sprites 2>/dev/null || true
+    # Regenerate per-user sprites for all cPanel accounts
+    if [[ -f /etc/trueuserdomains ]]; then
+        while IFS=: read -r _ user; do
+            user="${user// /}"
+            [[ -n "$user" ]] && cpapi2 --user="$user" Branding gensprites 2>/dev/null || true
+        done < /etc/trueuserdomains
+    fi
     echo "cPanel user plugin installed — users will see gniza Restore in Files section"
 else
     echo "cPanel not detected, skipping cPanel user plugin installation."