python3 verify_ed25519.py receipt-25236.json
Expected: exit 0 and a line beginning with "PASS receipt-25236.json"

python3 verify_ed25519.py receipt-25236-tampered.json
Expected: exit 1 and a line beginning with "FAIL receipt-25236-tampered.json"

The clean result checks the bundled Ed25519 signature only. It does not prove
issuer identity, event truth, WEX acceptance, witness independence, delivery,
settlement, or production status.
