Codex task: finalize functional model surface and product-suite release standards

[mdheller]

Mission

Finalize the functional model surface standards spine so downstream repos can implement releaseable CLIs, platform records, SourceOS carry refs, and lab profiles consistently.

This issue is designed for a Codex agent. Keep the change bounded and open a PR.

Scope

Build on the bootstrap PR and add concrete standards artifacts for:

• functional model surfaces
• SourceOS carry refs
• product-suite release contract
• devtools/lab profile selection
• Holmes language surface
• model routing, guardrails, agent registry, and platform promotion

Suggested files

• contracts/README.md
• examples/README.md
• tools/README.md
• examples/sourceos-carry-ref.example.json
• examples/product-release.example.json
• examples/devtools-profile.example.json
• tools/validate_examples.py
• Makefile

Acceptance criteria

• make validate validates all examples.
• Examples cover holmes, sourceos-ai, sourceos-devtools, model-router, guardrail-fabric, and agent-registry.
• Product release example requires version, checksums, SBOM, artifact attestation placeholder, Homebrew formula ref, and evidence output.
• SourceOS carry example enforces carry-only authority.
• Docs state that Homebrew installs orchestrators/clients, while ReleaseSet/BootReleaseSet installs OS artifacts.

Do not

• Do not implement runtime services here.
• Do not vendor model artifacts.
• Do not move platform runtime ownership out of prophet-platform.