Support authenticated organization skill catalogs

[Scriptception]

Problem

The CLI discovers only bundled official skills, so teams cannot distribute approved organization content with source authentication, version pinning, and the same validation guarantees.

User outcome

Authorized users can discover and install organization skills from a controlled catalog without copying them into the public package.

Scope

• Define a transport-neutral catalog protocol using signed indexes and immutable content digests.
• Support authenticated sources without storing credentials in lockfiles or logs.
• Apply the same metadata, capability, adapter, and structural validation as official skills.
• Define trust roots, publisher identity, revocation, and offline-cache behavior.

Non-goals

• Building a general artifact repository.
• Running downloaded executable content during catalog discovery.
• Embedding organization credentials in project files.

Acceptance criteria

• Catalog identity and index signatures are verified before listing or install.
• Every downloaded skill is pinned by immutable digest.
• Revoked or mismatched content fails closed with actionable output.
• Official and organization catalogs cannot silently shadow one another.

Validation

• Test valid, expired, revoked, tampered, unavailable, and replayed catalog fixtures.
• Inspect logs and lockfiles for credential or bearer-token leakage.

Relationships

• Depends on organization bundles, capability manifests, and provenance.
• Uses the same machine-readable catalog contract.