Move BackupsController and UpdateController to Admin/ namespace directly

Remove single-file Backup/ and Update/ subdirectories. These controllers
now sit alongside CompaniesController, UsersController, etc. in Admin/.

app/Http/Controllers/Admin/UpdateController.php

@@ -0,0 +1,104 @@
+<?php
+
+namespace App\Http\Controllers\Admin;
+
+use App\Http\Controllers\Controller;
+use App\Services\Update\Updater;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\File;
+
+class UpdateController extends Controller
+{
+    public function checkVersion(Request $request): JsonResponse
+    {
+        $this->ensureSuperAdmin();
+
+        set_time_limit(600);
+
+        $channel = $request->get('channel', 'stable');
+        $version = preg_replace('~[\r\n]+~', '', File::get(base_path('version.md')));
+
+        return response()->json(Updater::checkForUpdate($version, $channel));
+    }
+
+    public function download(Request $request): JsonResponse
+    {
+        $this->ensureSuperAdmin();
+
+        $request->validate(['version' => 'required']);
+
+        return response()->json([
+            'success' => true,
+            'path' => Updater::download($request->version),
+        ]);
+    }
+
+    public function unzip(Request $request): JsonResponse
+    {
+        $this->ensureSuperAdmin();
+
+        $request->validate(['path' => 'required']);
+
+        try {
+            return response()->json([
+                'success' => true,
+                'path' => Updater::unzip($request->path),
+            ]);
+        } catch (\Exception $e) {
+            return response()->json([
+                'success' => false,
+                'error' => $e->getMessage(),
+            ], 500);
+        }
+    }
+
+    public function copy(Request $request): JsonResponse
+    {
+        $this->ensureSuperAdmin();
+
+        $request->validate(['path' => 'required']);
+
+        return response()->json([
+            'success' => true,
+            'path' => Updater::copyFiles($request->path),
+        ]);
+    }
+
+    public function delete(Request $request): JsonResponse
+    {
+        $this->ensureSuperAdmin();
+
+        if (isset($request->deleted_files) && ! empty($request->deleted_files)) {
+            Updater::deleteFiles($request->deleted_files);
+        }
+
+        return response()->json(['success' => true]);
+    }
+
+    public function migrate(Request $request): JsonResponse
+    {
+        $this->ensureSuperAdmin();
+
+        Updater::migrateUpdate();
+
+        return response()->json(['success' => true]);
+    }
+
+    public function finish(Request $request): JsonResponse
+    {
+        $this->ensureSuperAdmin();
+
+        $request->validate([
+            'installed' => 'required',
+            'version' => 'required',
+        ]);
+
+        return response()->json(Updater::finishUpdate($request->installed, $request->version));
+    }
+
+    private function ensureSuperAdmin(): void
+    {
+        $this->authorize('manage update app');
+    }
+}