Add organization bundles and reproducible skill lockfiles

[Scriptception]

Problem

Users can install individual bundled skills, but teams cannot declare one approved set with exact versions, digests, target agents, scopes, and controlled update policy.

User outcome

A repository or organization can reproduce and audit its approved Skilldeck installation across agents.

Scope

• Define a lockfile for skill identity, version, digest, source, agent, render version, and scope.
• Define bundle manifests that reference an approved skill set.
• Add plan and apply commands that preview additions, updates, removals, conflicts, and local modifications.
• Preserve opt-in force behavior for changed local files.

Non-goals

• Managing agent application configuration unrelated to skills.
• Silently overwriting locally modified output.

Acceptance criteria

• The same bundle and lockfile produce byte-identical output in clean environments.
• Plan mode performs no writes and reports every target change.
• Digest or source mismatch fails before installation.
• Update and removal preserve the existing modification safety contract.

Validation

• Apply one bundle across at least three adapters and compare output digests.
• Test stale, modified, missing, conflicting, and orphaned installs.

Relationships

• Depends on catalog schema and lifecycle policy.
• Precedes authenticated organization catalogs.