Drop .install from the Windows install disk image name

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

build-windows-install-disk.sh

@@ -18,7 +18,7 @@
 #   Debian            wimtools dosfstools gdisk mtools udisks2
 #
 # Usage: build-windows-install-disk.sh [--force] ISO [OUTPUT.img]
-# OUTPUT defaults to the ISO path with ".install.img" in place of ".iso".
+# OUTPUT defaults to the ISO path with ".img" in place of ".iso".
 set -euo pipefail
 
 usage() {
@@ -39,7 +39,7 @@ if ((${#args[@]} < 1 || ${#args[@]} > 2)); then
   exit 2
 fi
 iso="${args[0]}"
-output="${args[1]:-${iso%.*}.install.img}"
+output="${args[1]:-${iso%.*}.img}"
 
 die() {
   printf 'Error: %s\n' "$1" >&2