curl -X POST https://api.sw4p.io/sdk/v1/solana/submit \
  -H "Content-Type: application/json" \
  -H "X-API-Key: sk_..." \
  -d '{
    "intent_id": "int_xyz789",
    "signed_transaction": "AQAAAA..."
  }'

{
  "intent_id": "int_xyz789",
  "status": "pending",
  "tx_signature": "5abc..."
}