docs: align release references with premday org move

[rokernel]

What changed

This updates the repo’s release-facing ownership references after moving the repository to the organization.

Release and image metadata

• update GoReleaser GHCR image targets to
• update GoReleaser build arg to
• update Dockerfile OCI source metadata to

README cleanup

• replace old GitHub and GHCR references with
• update attestation verification examples to
• standardize version examples to placeholders instead of hardcoded historical tags:
  • RELEASE_TAG=vX.Y.Z
  • PREVIOUS_RELEASE_TAG=vX.Y.Z
  • VERSION=X.Y.Z
• replace the disclaimer with production-ready wording that reflects human engineering plus AI-assisted workflows under human supervision and review

Why

The release workflow permissions were already correct, but release outputs and docs still pointed at the old owner. That would make the next release publish or document the wrong GHCR/image/source locations.

Files changed

• .goreleaser.yml
• Dockerfile
• README.md

Validation

• go test ./...
• go build ./...

Not included

• no module path migration
• no internal import path changes