Fork xmrcheckout for Wownero (WOW)

Minimal changes from upstream xmrcheckout to support Wownero:
- Rate provider: Nonlogs WOW-BTC via Kraken BTC/USD
- Subaddress derivation: Wownero network byte overrides (53/63/54)
- Payment URI scheme: wownero:
- Dockerfile: Wownero binaries from Codeberg
- Display text: Monero→Wownero, XMR→WOW throughout UI
- Default daemon: 192.168.88.235:34568
- Added wownero-logo.svg

File and folder structure kept identical to upstream for easy sync.

ui/components/btcpay-modal-bridge.tsx

@@ -0,0 +1,48 @@
+"use client";
+
+import { useEffect } from "react";
+
+type InvoiceStatus =
+  | "pending"
+  | "payment_detected"
+  | "confirmed"
+  | "expired"
+  | "invalid";
+
+type BtcpayModalBridgeProps = {
+  invoiceId: string;
+  status: InvoiceStatus;
+};
+
+const statusMap: Record<InvoiceStatus, string> = {
+  pending: "New",
+  payment_detected: "Processing",
+  confirmed: "Settled",
+  expired: "Expired",
+  invalid: "Invalid",
+};
+
+const postToParent = (payload: unknown) => {
+  if (typeof window === "undefined" || !window.parent) {
+    return;
+  }
+  window.parent.postMessage(payload, "*");
+};
+
+export default function BtcpayModalBridge({
+  invoiceId,
+  status,
+}: BtcpayModalBridgeProps) {
+  useEffect(() => {
+    postToParent("loaded");
+  }, []);
+
+  useEffect(() => {
+    postToParent({
+      invoiceId,
+      status: statusMap[status] ?? "new",
+    });
+  }, [invoiceId, status]);
+
+  return null;
+}