fix: add success/progress messages to pre-update backup

Previously the pre-update backup only showed a message on failure.
Now shows an info message that the backup is in progress and a
success message when it completes.

Claude-Session: https://claude.ai/code/session_01MbEjBtsSjPuTWhqqrMS2wG

source/packages/plg_system_mokosuitebackup/src/Extension/MokoSuiteBackup.php

@@ -390,11 +390,19 @@ final class MokoSuiteBackup extends CMSPlugin implements SubscriberInterface
 		$profileId = (int) $params->get('default_profile', 1);
 
 		try {
+			$app = Factory::getApplication();
+			$app->enqueueMessage('MokoSuiteBackup: ' . $description . ' in progress…', 'info');
+
 			$engine = new BackupEngine();
 			$result = $engine->run($profileId, $description, 'preaction');
 
-			if (!$result['success']) {
-				Factory::getApplication()->enqueueMessage(
+			if ($result['success']) {
+				$app->enqueueMessage(
+					'MokoSuiteBackup: ' . $description . ' completed successfully.',
+					'success'
+				);
+			} else {
+				$app->enqueueMessage(
 					'MokoSuiteBackup: ' . $description . ' failed — ' . $result['message'],
 					'warning'
 				);