docs(cookbook): restore Message, Error as own sidebar category below UI Interaction

Author: claude

docs/.vitepress/config.mjs

@@ -215,6 +215,13 @@ export default defineConfig({
               { text: "Title", link: "/development/specific/title" },
               { text: "Timer", link: "/development/specific/timer" },
               { text: "URL Handling", link: "/development/specific/url" },
+            ],
+          },
+          {
+            text: "Message, Error",
+            link: "/development/messages/messages",
+            collapsed: true,
+            items: [
               { text: "Message", link: "/development/messages/messages" },
               { text: "Error", link: "/development/messages/errors" },
               { text: "Logging", link: "/development/messages/logging" },