feat: SuperAdmin server-access kill switch gate

Add /super/settings endpoints and API middleware that returns generic 503 while keeping unlock routes whitelisted.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Http/Middleware/BlockServerAccess.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Cache;
+
+class BlockServerAccess
+{
+    public const CACHE_KEY = 'sa_server_access_blocked';
+
+    public function handle(Request $request, Closure $next)
+    {
+        $path = trim($request->path(), '/');
+        if ($this->isWhitelisted($path)) {
+            return $next($request);
+        }
+
+        if (Cache::get(self::CACHE_KEY)) {
+            return response()->json([
+                'message' => 'خطا در برقراری ارتباط با سرور',
+            ], 503);
+        }
+
+        return $next($request);
+    }
+
+    private function isWhitelisted(string $path): bool
+    {
+        $allowed = [
+            'super/settings',
+            'api/super/settings',
+        ];
+
+        foreach ($allowed as $item) {
+            if ($path === $item || str_ends_with($path, '/'.$item)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}