Fix: Runtime VAPID key fetching to avoid build-time environment dependency

src/app/api/notifications/config/route.ts

@@ -0,0 +1,7 @@
+import { NextResponse } from 'next/server';
+
+export async function GET() {
+    return NextResponse.json({
+        publicKey: process.env.NEXT_PUBLIC_VAPID_PUBLIC_KEY
+    });
+}

src/hooks/useNotifications.ts

@@ -52,9 +52,20 @@ export function useNotifications(reminderSettings: ReminderSettings) {
         throw new Error('Service Worker not ready');
       }
 
-      const publicVapidKey = process.env.NEXT_PUBLIC_VAPID_PUBLIC_KEY;
+      let publicVapidKey = process.env.NEXT_PUBLIC_VAPID_PUBLIC_KEY;
+
+      // If missing from build-time env, fetch it from runtime API
       if (!publicVapidKey) {
-        throw new Error('Missing VAPID key');
+        console.log('VAPID key missing from build-time env, fetching from runtime API...');
+        const configRes = await fetch('/api/notifications/config');
+        if (configRes.ok) {
+          const config = await configRes.json() as { publicKey?: string };
+          publicVapidKey = config.publicKey || '';
+        }
+      }
+
+      if (!publicVapidKey) {
+        throw new Error('Missing VAPID key (neither in build env nor runtime API). Please ensure NEXT_PUBLIC_VAPID_PUBLIC_KEY is set in Cloudflare secrets.');
       }
 
       // 1. Ensure we have a subscription