Improve read-only status check and disable logic for SteamOS

run.sh

@@ -66,8 +66,8 @@ prepare_steamos_package_install() {
     return
   fi
 
-  readonly_status="$(steamos-readonly status 2>/dev/null || true)"
-  if printf '%s\n' "$readonly_status" | grep -qi enabled; then
+  readonly_status="$(as_root steamos-readonly status 2>/dev/null || true)"
+  if printf '%s\n' "$readonly_status" | grep -Eqi '(^|[[:space:]])enable(d)?($|[[:space:]])'; then
     echo "Temporarily disabling the SteamOS read-only filesystem"
     as_root steamos-readonly disable
     STEAMOS_RESTORE_READONLY=1