curl --request POST \
  --url https://api.example.com/solana/permit \
  --header 'Content-Type: application/json' \
  --data '
{
  "airspace_pda": "<string>",
  "drone_pda": "<string>",
  "expires_at": 123
}
'

{
  "permit_pda": "<string>",
  "airspace_pda": "<string>",
  "drone_pda": "<string>",
  "granted_at": 123,
  "expires_at": 123,
  "tx": {
    "signature": "<string>",
    "slot": 123,
    "confirmation": "<string>",
    "fee_lamports": 123
  }
}