Add a search to the showcase

A search app bar looks through every section, example and component,
opens the section, or the example at its anchor on its page, and is
reached from anywhere with / or Ctrl+K. Section pages now carry their
own heading.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V9NnLxnPp8vaaurb3Z1MFy

src/Http/Controllers/ShowcaseController.php

@@ -3,6 +3,7 @@
 namespace NoNameWeb\LivewireMaterial\Http\Controllers;
 
 use Illuminate\Contracts\View\View;
+use Illuminate\Http\JsonResponse;
 use NoNameWeb\LivewireMaterial\Showcase\Sections;
 
 /**
@@ -22,4 +23,12 @@ class ShowcaseController
             'section' => $section,
         ]);
     }
+
+    /**
+     * The search's index, fetched when the search is first focused rather than written into every page.
+     */
+    public function search(): JsonResponse
+    {
+        return response()->json(Sections::index());
+    }
 }