Move artifacthub-pkg.yml from headlamp-sealed-secrets/ to repository
root to match ArtifactHub indexing requirements for Headlamp plugins.
This follows the same pattern as the polaris plugin and ensures
ArtifactHub can properly discover and index version 0.2.4 with the
correct checksum.
Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)
Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>