feat: complete Newsletter Campaigns Phase 1

- Add default campaign email template to DefaultTemplates.php
- Add toggle settings (campaign_scheduling, subscriber_limit_enabled)
- Add public unsubscribe endpoint with secure token verification
- Update CampaignManager to use NewsletterController unsubscribe URLs
- Add generate_unsubscribe_url() helper for email templates

includes/Modules/NewsletterSettings.php

@@ -75,6 +75,25 @@ class NewsletterSettings {
                 'placeholder' => __('I agree to receive marketing emails', 'woonoow'),
                 'default' => __('I agree to receive marketing emails and understand I can unsubscribe at any time.', 'woonoow'),
             ],
+            // Campaign Settings
+            'campaign_scheduling' => [
+                'type' => 'toggle',
+                'label' => __('Campaign Scheduling', 'woonoow'),
+                'description' => __('Enable scheduled campaigns. When on, you can schedule campaigns to be sent at a specific date and time.', 'woonoow'),
+                'default' => false,
+            ],
+            'subscriber_limit_enabled' => [
+                'type' => 'toggle',
+                'label' => __('Subscriber Limit', 'woonoow'),
+                'description' => __('Limit subscribers to 1000. When disabled, a custom database table will be created for unlimited subscribers.', 'woonoow'),
+                'default' => true,
+            ],
+            'subscriber_limit' => [
+                'type' => 'number',
+                'label' => __('Max Subscribers', 'woonoow'),
+                'description' => __('Maximum number of subscribers when limit is enabled (default: 1000)', 'woonoow'),
+                'default' => 1000,
+            ],
         ];
         
         return $schemas;