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/core/services/PaymentService.ts

@@ -130,7 +130,7 @@ export class PaymentService extends BaseService {
   /**
    * Pay Lightning invoice with user's wallet
    */
-  async payInvoiceWithUserWallet(
+  async payWithWallet(
     paymentRequest: string,
     requiredAmountSats?: number,
     options: PaymentOptions = {}
@@ -194,7 +194,7 @@ export class PaymentService extends BaseService {
   /**
    * Open external Lightning wallet
    */
-  openExternalLightningWallet(paymentRequest: string): void {
+  openExternalWallet(paymentRequest: string): void {
     if (!paymentRequest) {
       toast.error('No payment request available')
       return
@@ -223,7 +223,7 @@ export class PaymentService extends BaseService {
    * Handle payment with automatic fallback
    * Tries wallet payment first, falls back to external wallet
    */
-  async handlePaymentWithFallback(
+  async handlePayment(
     paymentRequest: string,
     requiredAmountSats?: number,
     options: PaymentOptions = {}
@@ -236,7 +236,7 @@ export class PaymentService extends BaseService {
     // Try wallet payment first if user has balance
     if (this.hasWalletWithBalance) {
       try {
-        return await this.payInvoiceWithUserWallet(
+        return await this.payWithWallet(
           paymentRequest, 
           requiredAmountSats, 
           options
@@ -248,7 +248,7 @@ export class PaymentService extends BaseService {
     }
 
     // Fallback to external wallet
-    this.openExternalLightningWallet(paymentRequest)
+    this.openExternalWallet(paymentRequest)
     return null // External wallet payment status unknown
   }