clan-config: stop using jsonschema at all for CLI

- instead use options.json coming from nixosOptionsDoc

lib/jsonschema/gen-options-json.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+expr='let pkgs = import <nixpkgs> {}; lib = pkgs.lib; in (pkgs.nixosOptionsDoc {options = (lib.evalModules {modules=[./example-interface.nix];}).options;}).optionsJSON.options'
+
+jq < "$(nix eval --impure --raw --expr "$expr")" > options.json