8ea048b988
U5 of the Claude Desktop .mcpb bundle plan. Splits the existing single- artifact release into three jobs. - build-skill keeps the prior bash skills/last30days/scripts/build-skill.sh flow, now uploaded via actions/upload-artifact instead of attaching directly so the final release step can pull from one place. - build-mcpb runs a matrix across darwin/arm64, darwin/amd64, and linux/amd64. Each entry installs printing-press@v4.8.0 (pinned to the version this PR was verified against; bump deliberately), runs mcp/scripts/sync-engine.sh, cross-compiles the Go binary with CGO_ENABLED=0 and the tag stamped into main.Version, and packages via `printing-press bundle`. Output filenames follow PP's DefaultBundleOutputPath convention. - release downloads every artifact (.skill + 3 .mcpb files) and attaches them to the GitHub release with generated notes. - Windows packaging is deferred: the manifest's entry_point cannot vary per platform within a single bundle, and Windows binaries need .exe naming for the OS to honor execve. A follow-up plan can ship a Windows-only bundle variant when there is demand. Verified locally: `printing-press bundle --skip-build --binary` against a host build produces a valid .mcpb (manifest.json + bin/<entry>). YAML parse-clean on both workflows.