StyleSeed update

Registry-first artifact boundary

When .styleseed/project.json and .styleseed/artifacts/index.json exist, resolve the requested artifact ID first, then read only .styleseed/bundles/<artifact-id>.md and .styleseed/manifests/<artifact-id>.json. Never fall back to the global legacy bundle for a registry project. Legacy projects may use .styleseed/effective-rules.md only when no registry exists.

Update the engine payload, not the user's product UI. A release version describes a published line; engineRevision identifies the exact maintained rules, skills, entry docs, and palette engine. Two installs with the same release version are not proven equal until their revisions match.

The checker verifies the payload for the active install channel. A repository/plugin checkout uses the full core inventory; a project-local Agent Skills install uses the executable skills inventory. The published endpoint must expose both the engine revision and, for a skills-only install, skillsRevision. The project manifest continues to record the engine revision that compiled its method bundle.

The bundled catalog also records distributionSource.channel. edge follows the mutable public repository state; stable follows the latest published release manifest. Do not compare a stable archive directly to edge main unless the user explicitly requests a channel switch.