[sttts]

Summary

Follow-up to ai-dynamo#17097 that changes supersession from deleting the immutable Run to canceling only its execution:

• when a newer Request generation arrives, write nvidia.com/dgdr-cancel-requested-by-generation onto the active non-terminal Run;
• retain the Run and wait for its authoritative Completed condition before creating the newest generation;
• keep the cancellation generation monotonic across coalesced Request updates and repair malformed, nonpositive, or stale marker values;
• grant the Request controller patch on Runs and regenerate the operator Role;
• preserve terminal Run references and Candidate history instead of losing them with the superseded Run object.

The Run controller side is implemented in ai-dynamo#17195: it accepts the marker only when its parsed generation is strictly newer than the Run's immutable Request-generation annotation, deletes the execution Job, and terminalizes the retained Run as Completed=True, reason=Superseded.

Refs DGH-1426 and ai-dynamo#17097.

Compatibility

This does not add a typed Kubernetes API field. The annotation is controller-owned causal intent. Invalid, equal, and older values never stop a Run; only a strictly newer generation does. An unchanged Request may continue running indefinitely.

Validation

• KUBEBUILDER_ASSETS=... go test ./internal/controller -run 'TestV1beta2Request|TestDGDRV1beta2Controller' -count=1: passed (10.739s)
• focused tables cover malformed, zero, negative, stale, equal, and newer cancellation generations
• repository pre-commit hooks: passed