fix(nwc): implement lookupInvoice for CLNRest and LndHub

CLNRest defined no lookupInvoice, so BackendUtils.call returned false
and every NWC lookup failed. LndHub inherited LND's /v1/invoice route,
which LndHub does not serve. CLN now uses listinvoices filtered by
payment hash, LndHub searches the user's invoice list.

backends/CLNRest.ts

@@ -266,6 +266,22 @@ export default class CLNRest {
         return this.postRequest('/v1/withdraw', request);
     };
     getMyNodeInfo = () => this.postRequest('/v1/getinfo');
+    // listinvoices filters natively by payment hash, and unlike the SQL query
+    // used by getInvoices it is not restricted to paid invoices
+    lookupInvoice = (data: any) =>
+        this.postRequest('/v1/listinvoices', {
+            payment_hash: data.r_hash
+        }).then((response: any) => {
+            const invoice = response?.invoices?.[0];
+            if (!invoice) {
+                throw new Error(
+                    localeString(
+                        'stores.NostrWalletConnectStore.error.invoiceNotFound'
+                    )
+                );
+            }
+            return invoice;
+        });
     getInvoices = (data?: any) =>
         this.postRequest('/v1/sql', {
             query: `SELECT label, bolt11, bolt12, payment_hash, amount_msat, status, amount_received_msat, paid_at, payment_preimage, description, expires_at FROM invoices ORDER BY created_index DESC LIMIT ${

backends/LndHub.ts

@@ -4,6 +4,7 @@ import LND from './LND';
 import LoginRequest from './../models/LoginRequest';
 import Base64Utils from './../utils/Base64Utils';
 import Bolt11Utils from './../utils/Bolt11Utils';
+import { localeString } from './../utils/LocaleUtils';
 import { Hash as sha256Hash } from 'fast-sha256';
 import { ecdsaSignDERHex } from '../utils/SigningUtils';
 
@@ -40,6 +41,23 @@ export default class LndHub extends LND {
         this.getRequest('/getuserinvoices').then((data: any) => ({
             invoices: data
         }));
+    // Overrides LND's /v1/invoice/{r_hash}, a route LndHub does not serve.
+    // LndHub has no per-invoice endpoint returning details — /checkpayment only
+    // answers paid/unpaid — so the user's invoice list is searched by hash.
+    lookupInvoice = (data: any) =>
+        this.getRequest('/getuserinvoices').then((invoices: any) => {
+            const invoice = (invoices || []).find(
+                (userInvoice: any) => userInvoice.payment_hash === data.r_hash
+            );
+            if (!invoice) {
+                throw new Error(
+                    localeString(
+                        'stores.NostrWalletConnectStore.error.invoiceNotFound'
+                    )
+                );
+            }
+            return invoice;
+        });
 
     createInvoice = (data: any) =>
         this.postRequest('/addinvoice', {