Does not support lifecycle, stopSignal, in pod spec.

## What version of Knative?

> 1.21.1

## Expected Behavior
I expect v1.RevisionSpec to embed members of PodSpec, including containers.lifecycle.StopSignal, as mentioned in the documentation https://knative.dev/docs/serving/reference/serving-api/#serving.knative.dev/v1.RevisionSpec. Relevant kubernetes docs (1.33+), https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.33/#lifecycle-v1-core.

## Actual Behavior
Trying to apply a knative service manifest specifying lifecycle within the podspec yields:
```
Error from server (BadRequest): error when creating "knative-test.yml": Service in version "v1" cannot be handled as a Service: strict decoding error: unknown field "spec.template.spec.containers[0].lifecycle"
```

## Steps to Reproduce the Problem
Apply the below manifest.
```yaml
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
name: lifecycle-test
spec:
template:
spec:
containers:
- image: gcr.io/knative-samples/helloworld-go
ports:
- containerPort: 8080
env:
- name: TARGET
value: "World"
lifecycle:
stopSignal: SIGTERM
```

Start with the serving.knative.dev/v1 RevisionSpec API and the Kubernetes Lifecycle reference linked in the issue, then reproduce the error with the provided lifecycle-test Service manifest. Trace how the pod spec is represented and validate that lifecycle.stopSignal is accepted without the strict decoding error.

Written by the indexing model from the issue text.