Add JSON schema generation for kubeconform CRD validation (#212)

## Summary
- New `ci/generate-schemas.sh` script that generates JSON schemas from three sources:
  1. Live cluster CRDs via `kubectl get crds`
  2. Offline CRD manifests (ArgoCD v3.3.2, Gateway API v1.5.1)
  3. Kubernetes v1.33.7 swagger spec for native types
- Schemas follow Datree catalog convention (`<group>/<Kind>_<version>.json`)
- `validate-apps.sh` and `validate-clusters.sh` check local schemas first, falling back to remote
- Fixes TLSRoute (and other CRD) schema validation failures in kubeconform

## Sources
- ArgoCD: `artifactapi.../argoproj/argo-cd/refs/tags/v3.3.2/manifests/ha/install.yaml`
- Gateway API: `artifactapi.../kubernetes-sigs/gateway-api/releases/download/v1.5.1/standard-install.yaml`
- Kubernetes: `artifactapi.../kubernetes/kubernetes/refs/tags/v1.33.7/api/openapi-spec/swagger.json`

Reviewed-on: #212
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

schemas/postgresql.cnpg.io/subscription_v1.json

@@ -0,0 +1,97 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "properties": {
+    "apiVersion": {
+      "type": "string"
+    },
+    "kind": {
+      "type": "string"
+    },
+    "metadata": {
+      "type": "object"
+    },
+    "spec": {
+      "properties": {
+        "cluster": {
+          "properties": {
+            "name": {
+              "default": "",
+              "type": "string"
+            }
+          },
+          "type": "object",
+          "x-kubernetes-map-type": "atomic"
+        },
+        "dbname": {
+          "type": "string",
+          "x-kubernetes-validations": [
+            {
+              "message": "dbname is immutable",
+              "rule": "self == oldSelf"
+            }
+          ]
+        },
+        "externalClusterName": {
+          "type": "string"
+        },
+        "name": {
+          "type": "string",
+          "x-kubernetes-validations": [
+            {
+              "message": "name is immutable",
+              "rule": "self == oldSelf"
+            }
+          ]
+        },
+        "parameters": {
+          "additionalProperties": {
+            "type": "string"
+          },
+          "type": "object"
+        },
+        "publicationDBName": {
+          "type": "string"
+        },
+        "publicationName": {
+          "type": "string"
+        },
+        "subscriptionReclaimPolicy": {
+          "default": "retain",
+          "enum": [
+            "delete",
+            "retain"
+          ],
+          "type": "string"
+        }
+      },
+      "required": [
+        "cluster",
+        "dbname",
+        "externalClusterName",
+        "name",
+        "publicationName"
+      ],
+      "type": "object"
+    },
+    "status": {
+      "properties": {
+        "applied": {
+          "type": "boolean"
+        },
+        "message": {
+          "type": "string"
+        },
+        "observedGeneration": {
+          "format": "int64",
+          "type": "integer"
+        }
+      },
+      "type": "object"
+    }
+  },
+  "required": [
+    "metadata",
+    "spec"
+  ],
+  "type": "object"
+}