curl -X POST "https://api.chargefy.io/v1/discounts/disc_123" \
-H "Authorization: Bearer {{API_KEY}}" \
-H "Content-Type: application/json" \
-d '{
"expires_at": "2026-06-01T00:00:00Z",
"metadata": {
"campaign": "black_friday"
},
"name": "Black Friday 20%"
}'