feat: add lightweight workflow run steps

[kj-podonos]

Summary

• regenerate the public SDK from backend contract 25958e9a
• expose lightweight workflow-run steps on sync, async, and raw clients
• add include_result, node_type, and node_id to workflows.runs.steps
• update the CLI, generated reference, manifest, and contract coverage

Compatibility

Workflow-step results are lightweight by default. Pass include_result=true to retrieve full result payloads; node_type and node_id filters can be combined.

The generated response model accepts older backend payloads that do not yet contain has_result or active_ports, which permits the required SDK-first rollout.

This feat: commit prepares the pre-1.0 minor release 0.12.0 through release-please. No version file was manually edited.

Validation

• fern check
• make lint
• make typecheck
• make test
• make build
• focused sync, async, raw, CLI, manifest, legacy-payload, and distribution contract suites
• independent spec and quality review: approved with no findings

Dependencies

• Backend: podonos/donut-be#444
• Frontend: podonos/donut-fe#511
• Linear: POD-617

Required eventual release order: SDK 0.12.0, backend, then frontend.

No merge, publish, release, deploy, or Sentry mutation is part of this PR.