POST /send

curl -X POST http://localhost:8080/send \
  -H "X-API-Key: lfy_your_key" \
  -H "Content-Type: application/json" \
  -d '{
    "to":"hello@example.com",
    "subject":"Welcome aboard",
    "body":"Thanks for signing up. Your account is ready."
  }'

{
  "to": "hello@example.com",
  "subject": "Welcome",
  "body": "<h1>Hello</h1><p>Thanks for signing up.</p>",
  "is_html": true
}

{
  "log_id": "c3be8e9f-8608-4d18-bb4e-e97a86be74d6",
  "status": "sent",
  "sent_at": "2026-08-04T09:19:47Z"
}