Add `terminationGracePeriodSeconds` field to `PodSpecPatch` to allow users to configure the pod termination grace period per TrainJob via `RuntimePatches`.
## What you would like to be added? Add `terminationGracePeriodSeconds` field to `PodSpecPatch` so users can configure the pod termination grace period per TrainJob via `RuntimePatches`. > **Depends on:** #3199 (`RuntimePatches` API) must be merged first. Currently, `PodSpecPatch` (introduced in #3199) supports these fields: - `serviceAccountName`, `nodeSelector`, `affinity`, `tolerations`, `volumes`, `initContainers`, `containers`, `schedulingGates`, `imagePullSecrets`, `securityContext` But it does not expose `terminationGracePeriodSeconds`, which is a standard `corev1.PodSpec` field. The field already exists in the TrainingRuntime CRD as part of the full embedded `corev1.PodSpec` (e.g., line 7507 in `trainer.kubeflow.org_trainingruntimes.yaml`), so runtime authors can set it. However, users cannot override it per-TrainJob. Proposed API change in `pkg/apis/trainer/v1alpha1/trainjob_types.go`: ```go type PodSpecPatch struct { // ... existing fields ... // terminationGr