Fix email environment variables for subscription system

- Add missing SMTP configuration variables
- Map GMAIL_USER/GMAIL_PASS to expected GOOGLE_EMAIL/GOOGLE_APP_PASSWORD
- Add RECIPIENT_EMAIL and SMTP_HOST/PORT/SECURE settings
- Fixes 'Failed to process subscription' error

docker-compose.yml

@@ -31,6 +31,12 @@ services:
       - PORT=3000
       - GMAIL_USER=${GMAIL_USER}
       - GMAIL_PASS=${GMAIL_PASS}
+      - SMTP_HOST=smtp.gmail.com
+      - SMTP_PORT=587
+      - SMTP_SECURE=false
+      - GOOGLE_EMAIL=${GMAIL_USER}
+      - GOOGLE_APP_PASSWORD=${GMAIL_PASS}
+      - RECIPIENT_EMAIL=${GMAIL_USER}
       - REDIS_URL=redis://redis:6379
       - REDIS_TOKEN=${REDIS_TOKEN}
     restart: unless-stopped