feat(proxy): upgrade Traefik image to v3.6

Upgrade default Traefik proxy configuration from v3.5 to v3.6, with Coolify version bump to beta.444.

🤖 Generated with Claude Code

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

bootstrap/helpers/proxy.php

@@ -212,7 +212,7 @@ function generateDefaultProxyConfiguration(Server $server, array $custom_command
             'services' => [
                 'traefik' => [
                     'container_name' => 'coolify-proxy',
-                    'image' => 'traefik:v3.5',
+                    'image' => 'traefik:v3.6',
                     'restart' => RESTART_MODE,
                     'extra_hosts' => [
                         'host.docker.internal:host-gateway',