Fix DB insert: remove add_prefix=false so table prefix is applied

Db::insert() was called with add_prefix=false, causing it to target
'simple_withdrawal_request' instead of '{prefix}simple_withdrawal_request'.
Dropping the explicit false restores the default (true).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

simple_withdrawalbutton.php

@@ -464,7 +464,7 @@ class Simple_withdrawalbutton extends Module
             'user_agent_hash' => $userAgentHash ?: null,
         ];
 
-        $ok = Db::getInstance()->insert(self::TABLE_REQUEST, $insert, false, true, Db::INSERT, false);
+        $ok = Db::getInstance()->insert(self::TABLE_REQUEST, $insert, false, true, Db::INSERT);
         if (!$ok) {
             return false;
         }