add global promotion deadline + fix grane medal

app/Policies/BasePolicy.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace App\Policies;
+
+use App\Models\User;
+
+class BasePolicy
+{
+    /**
+     * @param  \App\Models\User  $user
+     * @param  string  $ability
+     * @return void|bool
+     */
+    public function before(User $user, $ability)
+    {
+        if ($user->class >= User::CLASS_STAFF_LEADER) {
+            return true;
+        }
+    }
+}