[Vaibhav Patel (vpatelsj)]

Bugs

The v0.13.0 release exposed three release-path failures:

• Darwin kubectl-unbounded builds compiled Linux-only unix.Syncfs and unix.ST_NOEXEC references.
• The ARM64 netboot image downloaded a removed Ubuntu 24.04.4 tarball.
• A failed upstream release build skipped resolve, but release-upgrade treated empty outputs as a release-branch cut and ran publish with an empty tag.

Fix

• isolate Linux filesystem synchronization and mount inspection behind build tags, with explicit unsupported errors on other operating systems
• use stable Noble netboot file URLs for AMD64 and ARM64 instead of point-release URLs
• require resolve to succeed before the ordinary publish job can run

Validation

• both Darwin kubectl release binaries cross-compiled successfully
• full Go package build passed
• fsutil and release tests passed under the race detector
• golangci-lint: 0 issues
• actionlint passed
• AMD64 and ARM64 netboot images built successfully locally