Dart native-build patch 3.13.5-1 (macOS ARM64 preview)

Temporary macOS ARM64 build helper for Dart SDK #64556, pinned to stock Dart 3.13.5 (04bcd1036cdc799ac6564988f159ee454d42c822). This is an RK-distributed preview, not an official Dart SDK release.

It adds -D declarations and --format=aot-snapshot to Dart's existing hook-aware CLI builder. The compiler, hooks and runtime remain Dart's. The helper leaves the SDK unchanged and runs only when invoked for a build.

Download the macOS ARM64 archive (about 1.9 MB) and SHA256SUMS; verify the archive before extracting it. From a package whose locked dependencies have been resolved with the matching SDK:

/path/to/rk-dart-build /path/to/dart-sdk \
  --format=aot-snapshot -Dkeybay.application_id=keybay-cli \
  -t bin/keybay.dart -o /tmp/keybay-build

The output contains bundle/bin/<entry>.aot and its native libraries. Supply the matching runtime and complete signing/packaging as described in the included README. --format=exe remains the default.

The source archive includes the exact compilation sources, pinned provenance, notices, SDK patch and offline rebuild script. The binary archive includes notices and provenance. No SDK download manager, RK startup work or persistent helper cache was added.

Verified: offline source rebuild with original sources and Pub cache denied; executable and AOT native calls after relocation with declarations preserved; real Keypass adapter after Developer ID signing and archive relocation with development paths denied; replaced-library rejection; SDK version refusal and error propagation. RK's format, analysis, 1,088 functional tests and 8 publication tests also pass.

This ships the SDK workaround only. Native bundle integration in rk stage / rk release remains separate work. Linux targets, Keybay upgrade identity, notarization and Homebrew installation are not qualified by this preview. Retire it when the official SDK supports the options and passes the same checks.