Metis: define read-only MCP interface shape

[SaJaToGu]

Parent: #478

Goal

Define the first read-only MCP interface shape for Metis.

Scope

• Specify candidate tools for listing workers, listing models and finding execution options.
• Define request and response examples.
• Keep wake-up and job launch as later write actions.

Acceptance Criteria

• Interface document explains the read-only milestone.
• AIS can be a target client for find_execution_options.
• The interface avoids requiring AIS to know host-specific wake-up details.

[SaJaToGu]

Migrated to https://github.com/SaJaToGu/metis/issues/2 — Read-only MCP interface shape. This AIS issue stays open until the user verifies the migration.