feat: add CI test for k8s core deployment

[JaredforReal]

What type of PR is this?
feat: add CI test for k8s core deployment

What this PR does / why we need it:
This workflow tests the CORE semantic-router Kubernetes deployment.

Test Scope:

• Core deployment (namespace, pvc, deployment, service, configmap)
• Manifest validation (kubeconform)
• Service connectivity (gRPC, metrics, API ports)
• Security scanning (Trivy, Checkov)
• Basic syntax validation for observability and AI-Gateway configs

Out of Scope (planned for follow-up PRs):

• Observability stack deployment (Prometheus + Grafana)
• AI Gateway end-to-end testing (Envoy Gateway + InferencePool)

For Reviewer:
I'm new to setting up CI tests for Kubernetes on GitHub Actions, and would really appreciate any suggestions!

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[github-actions]

👥 vLLM Semantic Team Notification

The following members have been identified for the changed files in this PR and have been automatically assigned:

📁 Root Directory

Owners: @rootfs, @Xunzhuo
Files changed:

• .github/workflows/k8s-integration-test.yml

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🎉 Thanks for your contributions!

This comment was automatically generated based on the OWNER files in the repository.

[rootfs]

@JaredforReal this is great! Left a comment here.

[rootfs]

@JaredforReal thanks for making this happen! Would be great to have the e2e test integrated in the following up PRs!
cc @yossiovadia

[JaredforReal]

@JaredforReal thanks for making this happen! Would be great to have the e2e test integrated in the following up PRs! cc @yossiovadia

I would love to move things forward!