Refactor PaymentService methods for clarity and consistency

- Rename methods in PaymentService for improved readability: payInvoiceWithUserWallet to payWithWallet, openExternalLightningWallet to openExternalWallet, and handlePaymentWithFallback to handlePayment.
- Update related composables (useTicketPurchase, useLightningPayment) to reflect method name changes, ensuring consistent usage across the application.
- Modify RelayHub initialization process to set relay URLs before calling initialize, enhancing configuration clarity.
- Remove legacy compatibility flags in RelayHub to streamline the codebase and improve maintainability.

src/modules/events/composables/useTicketPurchase.ts

@@ -68,7 +68,7 @@ export function useTicketPurchase() {
   // Pay with wallet - delegate to PaymentService
   async function payWithWallet(paymentRequest: string) {
     try {
-      await paymentService.payInvoiceWithUserWallet(paymentRequest, undefined, {
+      await paymentService.payWithWallet(paymentRequest, undefined, {
         showToast: false // We'll handle success notifications in the ticket purchase flow
       })
       return true
@@ -179,7 +179,7 @@ export function useTicketPurchase() {
   // Open Lightning wallet - delegate to PaymentService
   function handleOpenLightningWallet() {
     if (paymentRequest.value) {
-      paymentService.openExternalLightningWallet(paymentRequest.value)
+      paymentService.openExternalWallet(paymentRequest.value)
     }
   }