Following best practices for release format transitions:
- build-release.sh now generates both formats from same sha256sum run
- Workflow uploads both checksums.txt and individual .sha256 files
- Validation ensures both formats exist and match
This provides a safe transition period for users with older install scripts
while maintaining the cleaner checksums.txt format going forward. After 2-3
releases when most users have updated scripts, we can remove .sha256 generation.
Related: Install script already supports both formats (falls back gracefully).
rcourtman
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