Run the conformance gate against agents-api

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What to build

agents-api runs the conformance gate against its own booted application.

One constraint is specific to this service: its operations reach Kubernetes, so write fuzzing must never run against a live cluster. The scheduled full run needs an isolated target.

Acceptance criteria

• Read-only operations are fuzzed on every pull request and the gate joins the pipeline aggregator
• Write fuzzing never touches a live cluster
• The undeclared-status-code check is active, so an undocumented failure path fails the gate
• Confirmed to fail against a deliberately non-conforming build

Blocked by

• Reusable Schemathesis conformance workflow
• Adopt the customizer and annotate the domain error codes