CI for Helm chart

[aliok]

Add CI to validate the Helm chart on every PR: linting, template rendering validation, and install testing on a Kind cluster. Also add a Makefile target for local validation.

See helm/kind-action.

[aliok]

This issue should also include CRD sync verification. The Helm chart from #155 has a static copy of the CRD in dist/chart/crds/, which can silently drift when controller-gen updates config/crd/bases/.

Proposed Makefile targets:

• make helm-sync runs make manifests then copies config/crd/bases/*.yaml to dist/chart/crds/
• make helm-verify: runs helm-sync then fails if git diff --exit-code dist/chart/crds/ detects drift

The verify target should run in CI alongside helm lint and helm template. This make X && git diff --exit-code pattern is already common in kubernetes-sigs projects for verifying generated code hasn't drifted (e.g., https://github.com/kubernetes-sigs/kro/blob/main/Makefile outputs CRDs directly to helm/crds/)

[aliok]

Another thing, once we have #157, we should run that in the CI as well.

[sats-23]

/assign