v0.47.3

Docker image metadata and MCP Registry reruns now handle the failure modes that
appeared in the Claudebox, Codexbox, and Pibox release jobs.

- Docker Hub short descriptions now use Docker Hub's 100 UTF-8 byte limit,
  rather than a character count. Both single-image and multi-image jobs keep
  whole Unicode characters and reject invalid direct input before
  authentication.
- MCP Registry publishing now reads the exact public version before OIDC login.
  A matching existing entry is a successful no-op. A different immutable entry
  fails. A duplicate response is accepted only after the Registry returns the
  exact expected metadata.