Wire bundled mosh release flow

[binaricat]

Summary

• Resolve the bundled mosh-client binary release during package builds instead of requiring every run to provide one manually.
• Keep package builds self-contained by using an explicit input or repo variable first, then falling back to the latest non-draft mosh-bin-* release.
• Keep official Windows packaging aligned with current bundled Mosh coverage by shipping Windows x64 only until win32-arm64 mosh binaries exist.
• Document the flow and cover resolver behavior, including paginated GitHub Release lookup, with tests.

Validation

• npm test
• npm run lint
• git diff --check
• Ruby YAML parse for build.yml, build-mosh-binaries.yml, and test.yml
• Release note generation check confirms Windows arm64 download links are not emitted
• Multi-agent review rounds: initial findings fixed, final narrow review clean

Follow-up after merge

Run build-mosh-binaries once with release_tag like mosh-bin-1.4.0-1. After that, package builds should pick it up automatically from the latest mosh-bin-* release, or from MOSH_BIN_RELEASE if explicitly set.