ci(release): release only from main - #44

The pull request removes the reviewed-epic release mode, restoring release.yml to its pre-7f09f60 state and updating the release-workflow tests accordingly; the description accurately covers both the workflow and test changes, and the workflows path rules show no widening of permissions, no newly unpinned action, and no untrusted context interpolated into a shell. _The code index is behind this pull request (indexed at `dcab2fd03d80`), so retrieved context may be out of date._

No findings.