fix: implement InstallerScriptInterface for Joomla 6 compatibility

Script wasn't running — Joomla 6 requires InstallerScriptInterface.
Also added debug file_put_contents to confirm execution.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/script.php

@@ -20,9 +20,10 @@ defined('_JEXEC') or die;
 
 use Joomla\CMS\Factory;
 use Joomla\CMS\Installer\InstallerAdapter;
+use Joomla\CMS\Installer\InstallerScriptInterface;
 use Joomla\CMS\Log\Log;
 
-class Tpl_MokocassiopeiaInstallerScript
+class Tpl_MokocassiopeiaInstallerScript implements InstallerScriptInterface
 {
     private const MIN_PHP    = '8.1.0';
     private const MIN_JOOMLA = '4.4.0';
@@ -77,6 +78,13 @@ class Tpl_MokocassiopeiaInstallerScript
 
     public function postflight(string $type, InstallerAdapter $parent): bool
     {
+        // Debug: write directly to confirm script runs
+        @file_put_contents(
+            JPATH_ROOT . '/administrator/logs/bridge_debug.txt',
+            date('Y-m-d H:i:s') . " postflight called, type={$type}\n",
+            FILE_APPEND
+        );
+
         if ($type === 'update') {
             $this->log('=== MokoCassiopeia → MokoOnyx bridge ===');
             $this->bridge();