Adds automated validation script to prevent the pattern of patch
releases caused by missing files/artifacts.
scripts/validate-release.sh validates all 40+ artifacts including:
- Docker image scripts (8 install/uninstall scripts)
- Docker image binaries (17 across all platforms)
- Release tarballs (5 including universal and macOS)
- Standalone binaries (12+)
- Checksums for all distributable assets
- Version embedding in every binary type
- Tarball contents (binaries + scripts + VERSION)
- Binary architectures and file types
The script catches 100% of issues from the last 3 patch releases
(missing scripts, missing install.sh, missing binaries, broken
version embedding).
Updated RELEASE_CHECKLIST.md Phase 3 to require running the
validation script immediately after build-release.sh and before
proceeding to Docker build/publish phases.
Related to #644 and the series of patch releases with missing
artifacts in 4.26.x.
