Add a second macOS shipping channel alongside the App Store build:
- New VniDropDirect target (Release-Direct config) sharing VniDrop's sources via
an AppBase target template; links Sparkle behind the DIRECT_DISTRIBUTION flag so
the App Store binary never bundles a self-updater. arm64-only (core is arm64).
- Sparkle updater (SparkleUpdater.swift) + "Check for Updates" menu, compiled only
under DIRECT_DISTRIBUTION; Info.plist SUFeedURL points at the GitHub Release
/latest/download/appcast.xml, non-sandboxed entitlements for Developer ID.
- build-dmg.sh (archive → Developer ID export → DMG → sign → notarize → staple),
generate-appcast.sh, and ExportOptions-DeveloperID.plist.
- apple-release.yml: on tag v*.*.*, build/notarize the DMG, publish the GitHub
Release with appcast, and push the Homebrew cask to sudosylabs/homebrew-vnidrop.
apple.yml gains a PR compile-check of the direct target.
- CFBundleVersion is stamped at build time as a UTC YYMMDD.HHMM timestamp for both
channels, replacing the hand-maintained build number.
- Docs (RELEASE-MACOS.md, README), cask template + tap README, localized
updates_check string, Makefile targets, gitignore for dist/ artifacts.
