Remove prerelease release recovery machinery

[rmcdaniel]

Summary

• delete the scheduled prerelease release-plan recovery workflow
• delete its copied resolver, publication, authority, conformance, fixture, and test implementation
• keep the ordinary direct tag/manual release workflow and all native build, checksum, attestation, installer, and exact-source checks
• remove the obsolete release-plan input from direct releases

Validation

• 881 PHPUnit tests pass (17,212 assertions; one existing skip)
• 18 Node release metadata/channel tests pass
• 8 native prerequisite tests pass
• actionlint workflow validation passes
• public-boundary and diff checks pass

Advances durable-workflow/.github#115.