Add JSON schema generation for kubeconform CRD validation

- ci/generate-schemas.sh extracts schemas from live cluster CRDs via kubectl
- Generated schemas committed to schemas/ for CI use
- Run `make schemas` to regenerate after CRD or K8s version changes
- validate-apps.sh and validate-clusters.sh check local schemas first
- CRD instances (Gateway, TLSRoute, Pooler, etc.) now validated instead of skipped
- CustomResourceDefinition meta-type still skipped (no schema exists upstream)

Makefile

@@ -1,4 +1,4 @@
-.PHONY: build clean
+.PHONY: build clean schemas
 
 # Build a kustomization path to manifests directory
 # Usage: make build clusters/au-syd1/bootstrap
@@ -6,6 +6,10 @@ build:
 	@mkdir -p manifests/$(filter-out $@,$(MAKECMDGOALS))
 	@kustomize build --enable-helm $(filter-out $@,$(MAKECMDGOALS)) --output manifests/$(filter-out $@,$(MAKECMDGOALS))
 
+# Generate JSON schemas from CRDs and Kubernetes swagger spec (run manually, results committed)
+schemas:
+	@ci/generate-schemas.sh schemas
+
 # kubeconform
 kubeconform:
 	@ci/validate-apps.sh && \