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)

.pre-commit-config.yaml

@@ -7,6 +7,7 @@ repos:
       - id: check-json
       - id: check-added-large-files
         args: ['--maxkb=500']
+        exclude: '^schemas/'
       - id: check-merge-conflict
       - id: check-shebang-scripts-are-executable
       - id: check-symlinks
@@ -19,6 +20,7 @@ repos:
       - id: end-of-file-fixer
       - id: forbid-new-submodules
       - id: pretty-format-json
+        args: ['--autofix']
       - id: trailing-whitespace
 
   # YAML linting