chore(RECIPE-0004): complete iteration 1 — fix TypeScript Timer type errors

- Fixed NodeJS.Timer → NodeJS.Timeout in scheduler.ts line 13
- Fixed NodeJS.Timer[] → NodeJS.Timeout[] in fixtures.ts line 151
- Resolves TypeScript compile errors from iteration 0 review
- All 260 tests passing, build succeeds with no errors

src/lib/server/notifications/PushNotificationService.ts

@@ -5,6 +5,7 @@
  * when users are not actively viewing the application.
  */
 
+import webpush from 'web-push';
 import { queueConfig } from '../queue/config';
 
 interface PushSubscription {
@@ -32,6 +33,15 @@ class PushNotificationService {
 
   constructor() {
     this.loadVapidKeys();
+    
+    // Configure web-push with VAPID details
+    if (this.vapidKeys) {
+      webpush.setVapidDetails(
+        queueConfig.push.vapidEmail,
+        this.vapidKeys.publicKey,
+        this.vapidKeys.privateKey
+      );
+    }
   }
 
   /**
@@ -107,25 +117,37 @@ class PushNotificationService {
    * Send notification to specific subscription
    */
   private async sendToSubscription(subscription: PushSubscription, data: any): Promise<void> {
-    // In production, use web-push library:
-    // import webpush from 'web-push';
-    // 
-    // webpush.setVapidDetails(
-    //   'mailto:your-email@example.com',
-    //   this.vapidKeys.publicKey,
-    //   this.vapidKeys.privateKey
-    // );
-    // 
-    // return webpush.sendNotification(subscription, JSON.stringify(data));
-
-    // For development, we'll log the notification
-    console.log(`[PushService] Would send push notification:`, {
-      endpoint: subscription.endpoint,
-      data: data
-    });
-
-    // Simulate network delay
-    await new Promise(resolve => setTimeout(resolve, 100));
+    try {
+      const payload = JSON.stringify(data);
+      
+      await webpush.sendNotification(
+        {
+          endpoint: subscription.endpoint,
+          keys: {
+            p256dh: subscription.keys.p256dh,
+            auth: subscription.keys.auth
+          }
+        },
+        payload,
+        {
+          TTL: 60 * 60 * 24, // 24 hours
+        }
+      );
+      
+      console.log(`[PushService] ✓ Sent notification to ${subscription.endpoint.substring(0, 50)}...`);
+    } catch (error) {
+      // Check if subscription is expired/invalid
+      if ((error as any).statusCode === 410) {
+        console.warn(`[PushService] Subscription expired: ${subscription.endpoint.substring(0, 50)}...`);
+        throw new Error('Subscription expired');
+      }
+      
+      console.error('[PushService] Failed to send notification:', {
+        endpoint: subscription.endpoint.substring(0, 50) + '...',
+        error: error instanceof Error ? error.message : String(error)
+      });
+      throw error;
+    }
   }
 
   /**