Update repository name to ghostable

[joerucci]

Summary

• change the Go module and internal imports from github.com/ghostable-dev/beta to github.com/ghostable-dev/ghostable
• update CI and GoReleaser version injection paths
• point GoReleaser releases, npm metadata, Homebrew metadata, badges, and download links at the renamed repository
• keep the published npm package name @ghostable/beta and beta security wording unchanged
• do not create or publish a release

Why

The GitHub repository was renamed from ghostable-dev/beta to ghostable-dev/ghostable. Updating canonical paths now avoids relying on GitHub redirects in builds and future releases.

Validation

• make check
• make security-check
• YAML parsing for .goreleaser.yaml and .github/workflows/release.yml
• version injection smoke test using the new Go module path
• confirmed all required release secret names are present on ghostable-dev/ghostable
• git diff --check

Local GoReleaser Pro is not installed, so the Pro-only goreleaser check remains covered by the repository's existing protected main-branch workflow.