feat: enable onboarding

setting a custom constant is now not required any more

includes/feature.php

@@ -1,15 +1,17 @@
 <?php
 
-function podlove_is_onboarding_active()
-{
-  return (bool) defined('PODLOVE_ONBOARDING') && PODLOVE_ONBOARDING;
+// default service URL
+// If you want to host and use your own service, set the constant in your wp-config.php
+// define('PODLOVE_ONBOARDING', 'https://self-hosted-services.example.com/onboarding');
+if (!defined('PODLOVE_ONBOARDING')) {
+    define('PODLOVE_ONBOARDING', 'https://services.podlove.org/onboarding');
 }
 
 function podlove_get_onboarding_include()
 {
-  if (podlove_is_onboarding_active() && is_string(PODLOVE_ONBOARDING)) {
-    return PODLOVE_ONBOARDING;
-  } else {
+    if (is_string(PODLOVE_ONBOARDING)) {
+        return PODLOVE_ONBOARDING;
+    }
+
     return null;
-  }
 }

lib/ajax/ajax.php

@@ -922,9 +922,7 @@ public function banner_hide()
             exit;
         }
 
-        if (\podlove_is_onboarding_active()) {
-            Onboarding::set_banner_hide('true');
-        }
+        Onboarding::set_banner_hide('true');
     }
 
     public function get_license_url()

lib/modules/onboarding/onboarding.php

@@ -13,17 +13,15 @@ class Onboarding extends \Podlove\Modules\Base
 
   public function load()
   {
-    if (\podlove_is_onboarding_active()) {
-      add_action('admin_enqueue_scripts', [$this, 'add_scripts_and_styles']);
-      add_action('admin_notices', [$this, 'onboarding_banner']);
-      add_action('admin_menu', [$this, 'add_onboarding_menu'], 20);
-      add_action('rest_api_init', [$this, 'api_init']);
-    }
+    add_action('admin_enqueue_scripts', [$this, 'add_scripts_and_styles']);
+    add_action('admin_notices', [$this, 'onboarding_banner']);
+    add_action('admin_menu', [$this, 'add_onboarding_menu'], 20);
+    add_action('rest_api_init', [$this, 'api_init']);
   }
 
   public static function is_visible()
   {
-    return \podlove_is_onboarding_active();
+    return true;
   }
 
   public function onboarding_banner()