Complete Payment module: initiate/webhook/confirm/refund actions, Filament resources (T5.8-T5.13)

- InitiatePaymentAction + POST /api/v1/payments/{booking}/initiate
- Generic KBZ webhook (POST /api/v1/webhooks/{method}/{encryptBookingId?}),
  signature verification per KBZ's real callback spec, PaymentGatewayInterface::handleWebhook()
- ConfirmPaymentAction: idempotent confirmation, PaymentCompleted/PaymentFailed events,
  MarkBookingPaid listener
- RefundBookingAction + POST /api/v1/bookings/{booking}/refund: partial refunds validated
  against remaining balance, RefundProcessed event, MarkBookingRefunded listener
- CancelBookingAction now refunds confirmed bookings instead of rejecting; BookingPolicy::cancel
  requires process_refunds for confirmed bookings
- PaymentPlugin + PaymentResource/RefundResource Filament admin UI (read-only payments,
  refund list + Process action)
- Booking detail page now shows related payments
- Fix CACHE_STORE mismatch (database -> redis) so tagged route caching works
- CLAUDE.md: never run migrate:fresh/migrate:refresh/db:wipe on dev without being asked

app-modules/payment/src/Events/RefundProcessed.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Modules\Payment\Events;
+
+use Illuminate\Foundation\Events\Dispatchable;
+use Modules\Payment\Models\Refund;
+
+/**
+ * Dispatched once a Refund completes successfully — gateways/actions stay
+ * ignorant of Booking, so booking-status changes react to this event
+ * instead (domain.md §6, see MarkBookingRefunded).
+ */
+class RefundProcessed
+{
+    use Dispatchable;
+
+    public function __construct(public Refund $refund) {}
+}