Preserve Nexus service-operation fields during worker completion validation

[rmcdaniel]

Confirmed behavior

While testing worker payload validation for #134, an authenticated worker submitted start_service_operation with nonempty endpoint_name, service_name, operation_name and request_payload. The completion returned HTTP 422 claiming all three routing fields were missing.

WorkerController::completeWorkflowTask validates individual commands.* fields but does not include these Nexus fields. Laravel drops them from the validated command before WorkflowCommandNormalizer::preflightParallelMetadata checks required service-operation values. This is distinct from malformed Avro handling: valid routing fields are lost before payload validation.

Acceptance

• Preserve and validate the supported Nexus command fields through the HTTP worker-completion ingress.
• Exercise an SDK-shaped command through the real worker HTTP route, not only direct service/normalizer calls.
• Prove valid service-operation dispatch and persisted outcome; retain rejection of malformed values and namespace/lease authority checks.
• Cover the supported optional operation fields as well as the required names and payload.

Accepted next after #134. Keep this scoped to the public Server protocol and regression tests.

[rmcdaniel]

Fixed in #140 and released as Server 2.3.1 with Workflow 2.0.6. Required and optional fields, actual dispatch/completion, malformed payloads, namespace/lease authority and existing-call replay authorization are covered. All PR checks passed, followed by real HTTP validation using the published image and its bundled dependencies: #140 (comment). Task containers, network and volumes were removed.