Add JSON schema generation for kubeconform CRD validation

- ci/generate-schemas.sh generates schemas from CRD manifests and K8s swagger
- Sources: ArgoCD v3.3.2, Gateway API v1.5.1, Kubernetes v1.33.7
- Optionally fetches live cluster CRDs via kubectl when available
- Generated schemas committed to schemas/ for CI use
- Run `make schemas` to regenerate after CRD version bumps
- validate-apps.sh and validate-clusters.sh check local schemas first
- Remove all kubeconform skip lists — all resource types now have schemas

ci/validate-apps.sh

@@ -21,6 +21,6 @@ while IFS= read -r -d "" k; do
         -summary \
         -output pretty \
         -verbose \
-        -skip GpuDevicePlugin,LBNodeAgent,ServiceGroup \
+        \
         "${schema_args[@]}"
 done < <(find apps/overlays -name kustomization.yaml -print0)