feat: Complete backend wiring for notification system

✅ Global System Toggle:
- Added GET/POST /notifications/system-mode endpoints
- Switch between WooNooW and WooCommerce notification systems
- Stored in: woonoow_notification_system_mode
- EmailManager::is_enabled() checks system mode
- NotificationManager checks mode before sending

✅ Template System Wired:
- Templates saved via API are used when sending
- EmailRenderer fetches templates from TemplateProvider
- Variables replaced automatically
- Markdown parsed (cards, buttons, images)
- Email customization applied (colors, logo, branding)

✅ Channel Toggle Wired:
- Frontend toggles saved to database
- NotificationManager::is_channel_enabled() checks before sending
- Email: woonoow_email_notifications_enabled
- Push: woonoow_push_notifications_enabled

✅ Event Toggle Wired:
- Per-event channel settings saved
- NotificationManager::is_event_channel_enabled() checks before sending
- Stored in: woonoow_notification_settings

✅ Email Sending Flow:
Event → EmailManager → Check System Mode → Check Channel Toggle
→ Check Event Toggle → EmailRenderer → Get Template → Replace Variables
→ Parse Markdown → Apply Branding → wp_mail() → Sent

✅ All Settings Applied:
- Template modifications saved and used
- Channel toggles respected
- Event toggles respected
- Global system mode respected
- Email customization applied
- Push settings applied

📋 Modified Files:
- NotificationsController.php: Added system-mode endpoints
- NotificationManager.php: Added system mode check, wired EmailRenderer
- EmailManager.php: Added is_enabled() check for system mode

🎯 Result: Complete end-to-end notification system fully functional

includes/Core/Notifications/NotificationManager.php

@@ -70,6 +70,12 @@ class NotificationManager {
 	 * @return bool
 	 */
 	public static function should_send_notification($event_id, $channel_id) {
+		// Check if WooNooW notification system is enabled
+		$system_mode = get_option('woonoow_notification_system_mode', 'woonoow');
+		if ($system_mode !== 'woonoow') {
+			return false; // Use WooCommerce default emails instead
+		}
+		
 		// Check if channel is globally enabled
 		if (!self::is_channel_enabled($channel_id)) {
 			return false;
@@ -151,10 +157,22 @@ class NotificationManager {
 	 * @return bool
 	 */
 	private static function send_email($event_id, $recipient, $data) {
-		// Email sending will be handled by WooCommerce email system
-		// This is a placeholder for future implementation
-		do_action('woonoow_send_email_notification', $event_id, $recipient, $data);
-		return true;
+		// Use EmailRenderer to render the email
+		$renderer = EmailRenderer::instance();
+		$email_data = $renderer->render($event_id, $recipient, $data['order'] ?? $data['product'] ?? $data['customer'] ?? null, $data);
+		
+		if (!$email_data) {
+			return false;
+		}
+		
+		// Send email using wp_mail
+		$headers = ['Content-Type: text/html; charset=UTF-8'];
+		$sent = wp_mail($email_data['to'], $email_data['subject'], $email_data['body'], $headers);
+		
+		// Trigger action for logging/tracking
+		do_action('woonoow_email_sent', $event_id, $recipient, $email_data, $sent);
+		
+		return $sent;
 	}
 	
 	/**