feat(media-buy): resolve acceptance policy catalogs

[bokelley]

Closes #1069

Summary

• expose the beta.9 acceptance-policy catalog, profile, rule, requirement, context, and discovery types
• add a conservative buyer resolver with exact-byte catalog and JCS policy/profile digest verification
• compose seller-default and product profiles restrictively with typed advisory outcomes and fail-closed diagnostics
• harden catalog fetches with canonical HTTPS URLs, IP pinning, no redirects or credentials, bounded incremental decompression, caching, and capability invalidation
• document adopter usage and add strict public API/type-check coverage

Verification

• make test (7,436 selected tests)
• make lint typecheck
• make test-type-checks
• make check-type-ignore-contract validate-generated
• uv build and uv build --wheel
• live smoke against the training-agent beta.9 catalog and shared registry (catalog, policy, and embedded profile digests verified)

[aao-secretariat]

Ladon verdict: Approve

Approve — additive seller acceptance-policy discovery, no blocking or medium findings.

Checked:

• Full digest trust chain in acceptance.py (exact-byte catalog pin, JCS profile/policy pins, fail-closed to unknown).
• Bounded/timeout-guarded fetches with IP pinning, no redirects, no credential leakage.
• Compression-bomb defense in _bounded_http.py.
• Local-bundle $ref containment in schema_loader.py.
• Correct additive feat: semver signal on the public surface (new exports only, no breaking shape/type changes).

Decision-table walk:

• Rows 1: no critical/high findings.
• Row 2: gated_paths false — N/A.
• Rows 3–5: high_risk true but all reasons are (modified) with zero medium-or-higher findings; no (deleted) entries; no medium findings of any category. None fire.
• Row 6: no prior decision.
• Row 7: no no-auto-approve team match.
• Row 8: fewer than three medium findings (zero).
• Row 9: approve.

review_decision: REVIEW_REQUIRED does not gate here because gated_paths is false. High-risk modifications to __init__.py, _eager.py, and signing/** were reviewed and preserve their contracts with no findings.

[aao-secretariat]

Ladon verdict: Approve

Approve — clean pass on PR #1097.

This is an additive-only feature landing the adcp.acceptance advisory resolver plus its supporting surface: public-surface wiring in __init__.py, a bounded gzip/deflate reader (signing/_bounded_http.py), a named-schema validator (validation/schema_loader.py), and two optional core.Policy fields. The reviewer completed largest-file coverage on acceptance.py (1011 lines) and operational-readiness review: fetch is fail-closed on URL/redirect/credentials, digests verify exact bytes before parse, every external call is timeout-bounded, and missing information resolves to unknown (never allow).

No Critical/High/Medium findings. The change is additive, so there is no semver-signal concern (no removed/renamed public exports, no required→optional flips, no discriminated-union narrowing) and no import-layering issue.

high_risk is true, but all matching entries are (modified) files with no medium-or-higher finding against them — per the arbiter guidance, a modification with no reviewer concern is presumed safe and does not warrant escalation. No (deleted) reasons. gated_paths is false. No no-auto-approve team match. Prior decision was also approve.

Rows 1–8 do not fire → row 9: approve.