Skill Workshop adds a pending-proposal approval workflow with CLI/Gateway review and a skill_workshop agent tool

What this changes for operators

• Skill Workshop introduces a new pending-proposal lifecycle that an operator must approve or reject via CLI or Gateway before a skill takes effect, inserting a human-in-the-loop gate into skill provisioning.
• The skill_workshop agent tool lets agents themselves file proposals, expanding the automation surface; operators must decide who may review and who may self-approve.
• Decision is for the control-plane admin/skill-author: configure the review path and authority for skill proposals.