v1.1.0

What's changed

• Security: webhook errors no longer reveal the expected signature. Before, one failed request exposed the right signature, so anyone could forge a charge:confirmed event. Errors now return a generic response.
• Security: webhooks are refused when no webhook secret is configured.
• A charge is only completed when the amount actually paid matches the payment's amount and currency, and already completed payments are skipped.
• The payment is recorded once when both the success page and the webhook handle the same charge.
• Unknown charges and amount mismatches are acknowledged and logged, so Coinbase stops retrying them for days.
• Fixed crashes when the webhook created the payment, or when the success page was opened without a charge in the session.