Add ping endpoint, update-refresh prompt, and dark-mode polish

app/Http/Controllers/PingController.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace App\Http\Controllers;
+
+use App\Models\Setting;
+use Illuminate\Http\JsonResponse;
+
+class PingController extends Controller
+{
+    public function __invoke(): JsonResponse
+    {
+        $build = Setting::query()->where('key', 'build')->value('value');
+        $reportedBuild = $build !== null ? ((int) $build) + 1 : 1;
+
+        return response()->json([
+            'connect' => 'ok',
+            'version_status' => [
+                'build' => $reportedBuild,
+            ],
+            'notification_state' => false,
+        ]);
+    }
+}