Performs a destructive mutation to transition a workshop session state to 'archived'.

• Cascade Behavior: Atomically tearing down all related active enrollment fixtures.
• Idempotency: Non-idempotent lookup; subsequent DELETE operations on the same GUID scope will resolve to a 404 response.

⚠️ DESTRUCTIVE OPERATION

LLM/MCP clients MUST obtain explicit end-user confirmation before invoking: present the target resource with user-recognizable identifiers
and receive an affirmative response. Confirmation MUST NOT be inferred from dialogue or context.