Fix workflow-dispatch release tag verification

[KRISHNAMMurarka]

Summary

• make an explicit release tag take precedence over the workflow branch name
• bind the workflow environment to the requested immutable tag
• add a regression test for dispatch from main

Evidence

The protected v0.1.1 release stopped before publishing because GitHub sets GITHUB_REF_NAME to main for workflow dispatch. This change preserves the immutable tag and fixes verification without moving or deleting it.

Verification

• npm run check
• GITHUB_REF_NAME=main npm run release:verify -- v0.1.1
• Node 22, 24, and 26 test runs
• 16 tests pass; implementation coverage remains 100 percent

[edilec]

The failing release stopped before publication. The fix preserves the immutable tag, binds verification to the requested input, adds a regression test, and all required checks pass.