feat(experiments): hardware TEE attestation experiment runner

[imran-siddique]

What

Adds experiments/claim-hw-attestation/ — the experiment that exercises the real hardware TEE path, so everything is ready to run the moment a confidential VM is available.

Every other experiment runs software-only (attestation_assurance: none). This one:

• P1 detects a real provider (sev-snp / tdx / tpm), never software-only
• P2 confirms report.report_data equals the gateway-supplied nonce
• P3 confirms the measurement is a real value, not the dev placeholder
• P4 confirms a different nonce yields different report_data (freshness)
• P5 runs the provider-specific verifier over the raw hardware evidence
• P6 builds a full TRACE Claim from the real report and verifies it end to end (schema, Ed25519 signature, TEE key binding)

Safe everywhere

On a host with no TEE it prints SKIP and exits 0 — verified on this (non-TEE) machine. CI scope (ruff check src/ tests/, mypy src/, pytest tests/unit) is untouched, so nothing new can break the build. experiments/ is not in the lint scope (same as the other runners).

Uses the real APIs

Drives detect/get_attestation_report (cmcp_runtime.tee), generate_trace_claim (cmcp_runtime.audit), and verify_trace_claim + the per-provider verify_*_measurement functions (cmcp_verify). It reproduces the gateway's actual nonce construction (JWK thumbprint ‖ salt, per startup.py) so the verifier's key-binding check passes on hardware.

What still needs the vendor services (not just hardware)

P5 verifies format + measurement + nonce binding but not the silicon cert chain. AMD KDS (VCEK/VLEK), Intel DCAP (quote signature/TCB), and TPM EK chain validation appear under unverified_fields until wired into cmcp_verify. Documented in the README as the last hardware-dependent step.

Docs

experiments/claim-hw-attestation/README.md: hardware options (Azure DCasv5/DCesv6, GCP n2d/c3), the deploy → config → run → verify sequence, sample cmcp-config.yaml, expected output, and the cert-chain caveat. experiments/README.md index updated.

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