feat(ci): add CRD schema generation for kubeconform validation

Add scripts to extract OpenAPI v3 schemas from CRD definitions in all
kustomize overlays and write JSON schema files to ci/crd-schemas/ for
kubeconform validation. This allows kubeconform to validate CRD instances
(Elasticsearch, Kibana, CNPG Cluster, VictoriaMetrics, etc.) instead of
skipping or erroring on them.

- ci/generate-crd-schemas.py: extracts schemas from CRD YAML on stdin
- ci/generate-crd-schemas.sh: iterates overlays, pipes to Python script
- ci/validate-apps.sh, ci/validate-clusters.sh: add local schema-location fallback
- Makefile: add generate-schemas target
- add generate-schemas step to kubeconform woodpecker pipeline so schemas

ci/generate-crd-schemas.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+"""
+Extract OpenAPI v3 schemas from CRD YAML on stdin and write JSON schema files
+to the output directory for use with kubeconform.
+
+Usage: kustomize build ... | python3 ci/generate-crd-schemas.py <output-dir>
+"""
+import sys
+import json
+import os
+
+import yaml
+
+
+def main() -> int:
+    output_dir = sys.argv[1] if len(sys.argv) > 1 else "ci/crd-schemas"
+    count = 0
+
+    for doc in yaml.safe_load_all(sys.stdin):
+        if not doc or doc.get("kind") != "CustomResourceDefinition":
+            continue
+
+        group = doc["spec"]["group"]
+        kind = doc["spec"]["names"]["kind"]
+        group_dir = os.path.join(output_dir, group)
+        os.makedirs(group_dir, exist_ok=True)
+
+        for ver in doc["spec"].get("versions", []):
+            if not ver.get("served", True):
+                continue
+            schema = ver.get("schema", {}).get("openAPIV3Schema")
+            if not schema:
+                continue
+            fname = os.path.join(group_dir, f"{kind.lower()}_{ver['name']}.json")
+            with open(fname, "w") as f:
+                json.dump({"$schema": "http://json-schema.org/schema#", **schema}, f, indent=2)
+                f.write("\n")
+            print(f"  wrote {fname}", file=sys.stderr)
+            count += 1
+
+    return count
+
+
+if __name__ == "__main__":
+    print(main())