ci: recover release artifacts safely

[gabeosx]

Summary

• match the linked changelog heading generated by Release Please
• add a guarded manual recovery input that rebuilds an existing immutable release tag on a GitHub-hosted runner
• attach recovered artifacts without allowing a recovery run to publish to npm
• document the recovery command

Verification

• confirmed the release context resolves split-flap-elements-v0.2.0 and its existing GitHub Release
• confirmed the assertion matches the committed 0.2.0 changelog heading
• git diff --check passes
• the failed release run completed package validation and exact-tarball smoke testing before the old assertion

The existing v0.2.0 tag and GitHub Release are not deleted or rewritten.