feat: adopt AdCP 3.2.0-beta.6

[bokelley]

Summary

• sync the schema cache and generated Python models to AdCP 3.2.0-beta.6
• expose the new canonical creative formats and resolve generated export collisions
• normalize beta.6 signing operation values and update version-scoped compatibility behavior
• fail closed before MCP or A2A transport when beta.6-only reporting controls target an older seller
• refresh public API, registry, error-code, and conformance fixtures
• reconcile the adoption branch with the negotiation, governance, transport, registry, task-option, observability, and OAuth hardening now on main

Migration note

AdCP 3.2.0-beta.6 changes the schema representation of request_signing.required_for, warn_for, and supported_for. The SDK normalizes those generated values back to lists of plain strings, preserving the existing Python API and wire serialization. Adopter code can continue using ordinary string membership checks.

Validation

• make lint
• make typecheck-all
• make validate-generated
• changed Python files pass ruff format --check
• 437 focused compatibility, versioning, codegen, signing, canonical-format, and client-validation tests pass (2 skipped)
• full CI rerun against current main after branch synchronization

[bokelley]

Manual review requested to satisfy branch protection. All required CI gates are green across Python 3.10–3.13, Postgres conformance, schema generation, downstream imports, and storyboard/reference-seller checks. Ladon reported no blocking findings, then its runner failed after arbitration with Argument list too long while processing the 1,403-file generated schema update; that is reviewer infrastructure, not a code/test failure.

[bokelley]

Final Ladon pass on 731e249: Clean, with findings: []; no unresolved review threads. The code_review check is red only because the arbiter process cannot start after receiving the 1,403-file high-risk-path list (Argument list too long). This is reviewer infrastructure, not a code finding. All completed product CI remains green; final Python matrix jobs are still running.

[bokelley]

Final synchronized pass on 3f08642: all product CI is green across Python 3.10–3.13, schema validation, Postgres, downstream imports, CodeQL, and storyboards. Ladon explicitly reported no blocking or Medium findings after the migration note was corrected. Its check remains red only because the high-risk arbiter launcher cannot handle the 1,490-file generated path list; the reviewer itself completed successfully with no inline comments.