Fix deploy webhook: use putenv to set HOME before git pull

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

deploy.php

@@ -41,7 +41,8 @@ if ($ref !== 'refs/heads/main') {
 }
 
 // Run git pull (HOME must be set explicitly since PHP's shell_exec doesn't inherit it)
-$output = shell_exec('HOME=/var/www cd /var/www/html && git pull 2>&1');
+putenv('HOME=/var/www');
+$output = shell_exec('git -C /var/www/html pull 2>&1');
 
 http_response_code(200);
 header('Content-Type: text/plain');