fix(realtime): replace axios with native HTTP client

Remove axios from the realtime server dependencies to avoid header injection risk,
switch Docker builds to npm ci, and bump the realtime image version to 1.0.15.

config/constants.php

@@ -4,7 +4,7 @@ return [
     'coolify' => [
         'version' => '4.1.0',
         'helper_version' => '1.0.13',
-        'realtime_version' => '1.0.14',
+        'realtime_version' => '1.0.15',
         'railpack_version' => '0.22.0',
         'self_hosted' => env('SELF_HOSTED', true),
         'autoupdate' => env('AUTOUPDATE'),