Expose nodeSelector for operator and webhook

[faganihajizada]

Summary

The Helm chart did not document or wire nodeSelector for either the operator or webhook Deployment. Helm parsed --set operator.nodeSelector.foo=bar (and the webhook equivalent) into .Values without complaint and silently dropped the value at render time, since no template referenced it and the chart has no values.schema.json for validation.

This PR wires .Values.operator.nodeSelector and .Values.webhook.nodeSelector through templates/operator/deployment.yaml and templates/webhook/deployment.yaml using the same {{- with ... }} / toYaml | nindent 8 idiom already used for affinity and tolerations, documents the field in values.yaml with wording aligned to the sibling helm/slurm chart, regenerates the matching rows in the values table of helm/slurm-operator/README.md, and adds helm-unittest cases that assert the rendered field for both deployments.

Reproduction

helm template slinky-slurm-op helm/slurm-operator \
  --set operator.nodeSelector.foo=bar \
  --set webhook.nodeSelector.baz=qux | grep nodeSelector
# (no output — value silently dropped)

Checklist

• I have read CONTRIBUTING.md and the Code of Conduct.
• New or existing tests cover these changes (where applicable).
• Documentation is updated if user-visible behavior changes.

Breaking Changes

Not a breaking API change — nodeSelector was never a documented or supported field on either deployment, and default renders are unchanged (the field is omitted unless the user sets it).

There is a latent behavior change worth flagging: any operator who had been setting operator.nodeSelector or webhook.nodeSelector in their values file under the assumption it was being honored will now see the constraint take effect. They should verify their value does not pin pods to nodes that no longer match.

Testing Notes

The new helm-unittest cases (should add nodeSelector) sit alongside the existing should add affinity / should add tolerations tests in both tests/operator_deployment_test.yaml and tests/webhook_deployment_test.yaml, following the same shape and depth.