feat: auto-remove deprecated system plugin on install/upgrade

The install script now uninstalls plg_system_mokojoomhero if present,
cleaning up the old package extension remnant. Uses Joomla Installer
for proper DB and file cleanup. Non-critical — silently skips if the
plugin is already gone.

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

src/script.php

@@ -11,17 +11,48 @@
 
 defined('_JEXEC') or die;
 
+use Joomla\CMS\Factory;
 use Joomla\CMS\Filesystem\Folder;
 use Joomla\CMS\Installer\InstallerAdapter;
 
 class Mod_MokojoomheroInstallerScript
 {
-    public function postflight(string $type, InstallerAdapter $adapter): void
-    {
-        $heroesPath = JPATH_ROOT . '/images/heroes';
+	public function postflight(string $type, InstallerAdapter $adapter): void
+	{
+		// Create default image folder on fresh install
+		$heroesPath = JPATH_ROOT . '/images/heroes';
 
-        if (!is_dir($heroesPath)) {
-            Folder::create($heroesPath);
-        }
-    }
+		if (!is_dir($heroesPath)) {
+			Folder::create($heroesPath);
+		}
+
+		// Remove deprecated system plugin (was part of the old package extension)
+		$this->removeDeprecatedPlugin();
+	}
+
+	/**
+	 * Uninstall plg_system_mokojoomhero if it exists — no longer needed.
+	 */
+	private function removeDeprecatedPlugin(): void
+	{
+		try {
+			$db = Factory::getDbo();
+
+			$query = $db->getQuery(true)
+				->select($db->quoteName('extension_id'))
+				->from($db->quoteName('#__extensions'))
+				->where($db->quoteName('type') . ' = ' . $db->quote('plugin'))
+				->where($db->quoteName('folder') . ' = ' . $db->quote('system'))
+				->where($db->quoteName('element') . ' = ' . $db->quote('mokojoomhero'));
+			$db->setQuery($query);
+			$extensionId = (int) $db->loadResult();
+
+			if ($extensionId) {
+				$installer = new \Joomla\CMS\Installer\Installer();
+				$installer->uninstall('plugin', $extensionId);
+			}
+		} catch (\Exception $e) {
+			// Non-critical — plugin may already be gone
+		}
+	}
 }