rk 0.1.12

• macOS Dart CLIs now ship as a signed launcher, matching runtime and AOT
  module, without executable-memory exceptions. Linux retains single-file
  executables; both use the same artifact, verification and Homebrew pipeline.
• Binary projects can project public pubspec fields through
  dart_defines_from_pubspec without duplicating their values in release config.
• Bundled RK keeps a stable stage identity when run from its module directory,
  and installed RK uses the Dart SDK for pub.dev availability checks.
• rk init now selects every binary platform the release host can produce;
  macOS proposes its native archive plus both pure-Dart Linux cross-builds.
• Cross-built Linux artifacts always receive explicit Dart target flags, even
  when Docker or Podman is unavailable. Containers provide the optional smoke
  test; they are not a cross-compilation requirement.
• Multi-unit status checks now nest release targets beneath their unit instead
  of repeating the unit on every row.