Create broadcast

curl -X POST 'https://api.sndr.sh/v1/broadcasts' \
  -H "Authorization: Bearer $SNDR_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
    "name":       "June newsletter",
    "group_id":   "grp_4d8a0c5e-1f7",
    "from_email": "Acme <hello@acme.com>",
    "subject":    "June product update",
    "html":       "<h1>June update</h1><p>Here is what is new.</p>"
  }'

{
  "id":               "bca_9b3e6d12-a40",
  "organization_id":  "org_8d41c7a2-3f6",
  "name":             "June newsletter",
  "group_id":         "grp_4d8a0c5e-1f7",
  "from_email":       "\"Acme\" <hello@acme.com>",
  "subject":          "June product update",
  "html":             "<h1>June update</h1><p>Here is what is new.</p>",
  "status":           "draft",
  "total_recipients": 0,
  "sent_count":       0,
  "failed_count":     0,
  "created_at":       "2026-06-01T12:00:00Z"
}