Move global admin controllers from Admin to SuperAdmin namespace

Backup, Update, Modules, and global Settings controllers (mail config,
PDF config, disk management, global settings) are application-wide features
not scoped to a company. Move them from Admin/ to SuperAdmin/ to match the
v3.0 UI structure where these live under Administration.

Company-scoped settings controllers remain in Admin/Settings/.

app/Http/Controllers/V1/SuperAdmin/Backup/ApiController.php

@@ -0,0 +1,18 @@
+<?php
+
+// Implementation taken from nova-backup-tool - https://github.com/spatie/nova-backup-tool/
+
+namespace App\Http\Controllers\V1\SuperAdmin\Backup;
+
+use App\Http\Controllers\Controller;
+use Illuminate\Http\JsonResponse;
+
+class ApiController extends Controller
+{
+    public function respondSuccess(): JsonResponse
+    {
+        return response()->json([
+            'success' => true,
+        ]);
+    }
+}