Publish an evergreen DSH release asset

[diqierjia]

Summary

• pack the DSH npm artifact once and publish that exact tarball
• attach both the versioned filename and fixed stratagate-dsh.tgz alias to every GitHub Release
• apply the same fixed-name asset rule to staged artifact releases

Verification

• npm run check:dsh
• npm run test:dsh (56 tests)
• npm run build:dsh
• npm run verify:dsh
• verified both asset names have identical SHA-256 hashes
• parsed the workflow YAML and ran git diff --check