curl --request POST \
  --url https://api.example.com/solana/delivery \
  --header 'Content-Type: application/json' \
  --data '
{
  "drone_pda": "<string>",
  "airspace_pda": "<string>",
  "ipfs_cid": "<string>",
  "latitude": 123,
  "longitude": 123,
  "altitude_m": 123,
  "delivered_at": 123
}
'

{
  "signature": "<string>",
  "slot": 123,
  "confirmation": "<string>",
  "fee_lamports": 123
}