Consolidate the closed runtime recipe contract

[jeremi]

Outcome

Reduce drift between the release-lock producer, Rust verifier/renderer, Compose checker, fixtures, and runbook without turning Registryctl into a general orchestrator.

The existing 1.0 runtime recipe remains the behavioral baseline. This work should consolidate ownership after 1.0, not expand its command, mount, secret, or network vocabulary.

Design constraints

• One versioned closed contract owns supported products, actions, mounts, inputs, platforms, health probes, and hardening.
• Relay, Notary, Registryctl, and release tooling retain their current ownership boundaries.
• No arbitrary container, command, mount, secret-provider, network, or Kubernetes language is introduced.
• Generated Compose remains replaceable and operator integration remains outside Registryctl certification.
• Security-sensitive parity checks stay fail-closed and reviewable.

Definition of Done

• One authoritative versioned source produces or validates every runtime-recipe projection.
• Python and Rust no longer hand-maintain conflicting copies of fixed action shapes.
• Generated fixtures are reproducible and checked for drift.
• Platform pins, health ports, action inputs, network authority, mounts, and hardening have one parity gate.
• A compatibility policy describes how a future recipe version is introduced and retired.
• Clean-context Compose and released-artifact journeys remain green.

Non-goals

• Production orchestration.
• Parent Compose certification.
• Kubernetes support, which remains tracked separately.
• User-defined runtime recipes.