Migrate InvoiceService to dependency injection pattern

- Add INVOICE_SERVICE token to DI container
- Register InvoiceService in base module with proper lifecycle
- Update market store to use dependency injection instead of singleton
- Remove exported singleton from InvoiceService class
- Add comprehensive migration documentation with examples
- Maintain type safety with proper TypeScript interfaces

This migration eliminates the legacy singleton pattern and improves:
- Testability through service injection
- Modular architecture with clear boundaries
- Single source of truth for service instances
- Consistent dependency injection patterns

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/modules/market/stores/market.ts

@@ -1,11 +1,10 @@
 import { defineStore } from 'pinia'
 import { ref, computed, readonly, watch } from 'vue'
-import { invoiceService } from '@/core/services/invoiceService'
 import { paymentMonitor } from '../services/paymentMonitor'
 import { nostrmarketService } from '../services/nostrmarketService'
 import { useAuth } from '@/composables/useAuthService'
 import { injectService, SERVICE_TOKENS } from '@/core/di-container'
-import type { LightningInvoice } from '@/core/services/invoiceService'
+import type { LightningInvoice, InvoiceService } from '@/core/services/invoiceService'
 
 
 import type {
@@ -18,6 +17,7 @@ import type {
 export const useMarketStore = defineStore('market', () => {
   const auth = useAuth()
   const storageService = injectService(SERVICE_TOKENS.STORAGE_SERVICE) as any
+  const invoiceService = injectService(SERVICE_TOKENS.INVOICE_SERVICE) as InvoiceService
   // Core market state
   const markets = ref<Market[]>([])
   const stalls = ref<Stall[]>([])