Add background notifications and fix Discord/Slack notification bugs

Background Notification Features:
- Implement Web Push Notifications for alerts when browser is minimized
- Add Service Worker for persistent background notification support
- Integrate Page Visibility API to detect when page is in background
- Add browser notification permission request with user consent flow
- Create more aggressive background polling (10 seconds) when page hidden
- Add vibration patterns for mobile device alerts

Bug Fixes:
- Fix Discord/Slack notification parameter order bug preventing delivery
- Add comprehensive logging for notification debugging
- Correct webhook function signatures for proper data passing

Mobile Enhancements:
- Support system notifications on Android browsers
- Add click-to-focus functionality for notifications
- Implement background alert system for multitasking
- Add notification button with visual feedback

🤖 Generated with [Claude Code](https://claude.ai/code)

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

includes/class-twp-notifications.php

@@ -9,23 +9,34 @@ class TWP_Notifications {
      * Send notification to Discord and/or Slack
      */
     public static function send_call_notification($type, $data) {
+        // Log notification attempt
+        error_log("TWP: Attempting to send {$type} notification with data: " . json_encode($data));
+        
         // Check if notifications are enabled for this type
         if (!self::is_notification_enabled($type)) {
+            error_log("TWP: {$type} notifications are disabled");
             return;
         }
 
         $message = self::format_message($type, $data);
+        error_log("TWP: Formatted message: " . $message);
         
         // Send to Discord if configured
         $discord_url = get_option('twp_discord_webhook_url');
         if (!empty($discord_url)) {
-            self::send_discord_notification($discord_url, $message, $data);
+            error_log("TWP: Sending Discord notification to: " . substr($discord_url, 0, 50) . "...");
+            self::send_discord_notification($discord_url, $data, $message);
+        } else {
+            error_log("TWP: Discord webhook URL not configured");
         }
         
         // Send to Slack if configured
         $slack_url = get_option('twp_slack_webhook_url');
         if (!empty($slack_url)) {
-            self::send_slack_notification($slack_url, $message, $data);
+            error_log("TWP: Sending Slack notification to: " . substr($slack_url, 0, 50) . "...");
+            self::send_slack_notification($slack_url, $data, $message);
+        } else {
+            error_log("TWP: Slack webhook URL not configured");
         }
     }