refactor: update marketplace JSON schema in live app server examples

Update the marketplace configuration structure to align with the latest
schema requirements. This includes adding a display name to the interface
object and nesting installation and authentication policies within a
dedicated policy object.

Author: nshkrdotcom

examples/live_app_server_plugins.exs

@@ -96,15 +96,20 @@ defmodule CodexExamples.LiveAppServerPlugins do
     marketplace_json = """
     {
       "name": "#{marketplace_name}",
+      "interface": {
+        "displayName": "Codex SDK Demo Marketplace"
+      },
       "plugins": [
         {
           "name": "#{plugin_name}",
           "source": {
             "source": "local",
             "path": "./plugins/#{plugin_name}"
           },
-          "installPolicy": "AVAILABLE",
-          "authPolicy": "ON_INSTALL",
+          "policy": {
+            "installation": "AVAILABLE",
+            "authentication": "ON_INSTALL"
+          },
           "category": "Design"
         }
       ]