fix: Set Livewire asset_url to null for subdirectory support

ASSET_URL was being used as the script src, causing:
<script src="https://domain.com/kb">

Setting asset_url to null lets Livewire use the correct default path.

src/config/livewire.php

@@ -15,7 +15,7 @@
     |
     */
 
-    'asset_url' => env('ASSET_URL'),
+    'asset_url' => null,
 
     /*
     |--------------------------------------------------------------------------