Adds scripts/build-dmg-linux.sh + 'npm run build:dmg': - virt-make-fs creates an HFS+ volume inside a plain 400M image file (guestfs appliance; never touches block devices) - libdmg-hfsplus converts it to compressed UDZO .dmg (real koly/UDIF) - app + /Applications drag-install symlink; secret scan on extracted contents - BUILD_GUIDE documents the route + Gatekeeper first-run note Verified end-to-end: rc=0, 121MB DMG with valid koly trailer, extractall round-trip reproduced the full 264MB app, secrets scan clean.
