Remove useNostrOrders composable and related Checkout page

- Delete the useNostrOrders composable as it is no longer needed.
- Update MerchantStore.vue to utilize nostrmarketService for publishing orders instead of the removed composable.
- Refactor market store to check the readiness of nostrmarketService instead of useNostrOrders.
- Remove the Checkout.vue page, streamlining the checkout process and improving code maintainability.

src/modules/market/components/MerchantStore.vue

@@ -320,12 +320,11 @@ import {
   BarChart3
 } from 'lucide-vue-next'
 import type { OrderStatus } from '@/stores/market'
-import { nostrOrders } from '@/composables/useNostrOrders'
+import { nostrmarketService } from '../services/nostrmarketService'
 import { auth } from '@/composables/useAuth'
 
 const router = useRouter()
 const marketStore = useMarketStore()
-const nostrOrdersComposable = nostrOrders
 
 // Local state
 const isGeneratingInvoice = ref<string | null>(null)
@@ -502,7 +501,7 @@ const sendInvoiceToCustomer = async (order: any, invoice: any) => {
 
     // Send the updated order to the customer via Nostr
     // This will include the invoice information
-    await nostrOrdersComposable.publishOrderEvent(updatedOrder, order.buyerPubkey)
+    await nostrmarketService.publishOrder(updatedOrder, order.buyerPubkey)
     
     console.log('Updated order with invoice sent via Nostr to customer:', order.buyerPubkey)
   } catch (error) {

src/modules/market/services/nostrmarketService.ts

@@ -76,6 +76,18 @@ export class NostrmarketService {
     return hub
   }
 
+  /**
+   * Check if the service is ready for Nostr operations
+   */
+  get isReady(): boolean {
+    try {
+      this.getAuth()
+      return true
+    } catch {
+      return false
+    }
+  }
+
   /**
    * Convert hex string to Uint8Array (browser-compatible)
    */

src/modules/market/stores/market.ts

@@ -1,6 +1,5 @@
 import { defineStore } from 'pinia'
 import { ref, computed, readonly, watch } from 'vue'
-import { nostrOrders } from '@/composables/useNostrOrders'
 import { invoiceService } from '@/lib/services/invoiceService'
 import { paymentMonitor } from '@/lib/services/paymentMonitor'
 import { nostrmarketService } from '../services/nostrmarketService'
@@ -595,7 +594,7 @@ export const useMarketStore = defineStore('market', () => {
 
   const sendPaymentConfirmation = async (order: Order) => {
     try {
-      if (!nostrOrders.isReady.value) {
+      if (!nostrmarketService.isReady) {
         console.warn('Nostr not ready for payment confirmation')
         return
       }
@@ -612,7 +611,7 @@ export const useMarketStore = defineStore('market', () => {
       // }
 
       // Send confirmation to customer
-      await nostrOrders.publishOrderEvent(order, order.buyerPubkey)
+      await nostrmarketService.publishOrder(order, order.buyerPubkey)
       
       console.log('Payment confirmation sent via Nostr')
     } catch (error) {