Add WebhookRateLimiter service with IP-based rate limiting for webhook
endpoints to prevent rate limit exhaustion attacks against legitimate
payment webhooks.
Changes:
- Add WebhookRateLimiter service with per-IP tracking
- Default: 60 req/min for unknown IPs, 300 req/min for trusted gateway IPs
- Support CIDR ranges for IP allowlisting
- Configure via commerce.webhooks.rate_limits and trusted_ips
- Update BTCPayWebhookController and StripeWebhookController
- Return proper 429 responses with Retry-After headers
- Replace global throttle:120,1 middleware with granular controls
- Add comprehensive tests for rate limiting behaviour
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Add missing files from P1-040/P1-041 implementation:
- CheckoutRateLimitException for 429 responses when rate limit exceeded
- FraudAssessment data object for fraud scoring results
- FraudService for velocity checks and Stripe Radar integration
- Register services in Boot.php
- Add fraud detection configuration in config.php
- Add CouponServiceTest for input sanitisation
The CheckoutRateLimiter (already tracked) is now properly integrated with
the exception handling, and the FraudService provides defence-in-depth
with velocity-based and geo-anomaly detection.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
