Remove legacy compatibility layer and enforce modular architecture

- Delete src/stores/market.ts compatibility re-export file
- Update 15 files to import from proper module path @/modules/market/stores/market
- Add necessary type exports to market store for external consumers
- Remove empty src/stores/ directory completely
- Enforce clean modular architecture without global store shortcuts

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

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

src/modules/market/services/nostrmarketService.ts

@@ -1,6 +1,6 @@
 import { finalizeEvent, type EventTemplate, nip04 } from 'nostr-tools'
 import { BaseService } from '@/core/base/BaseService'
-import type { Stall, Product, Order } from '@/stores/market'
+import type { Stall, Product, Order } from '@/modules/market/stores/market'
 
 export interface NostrmarketStall {
   id: string

src/modules/market/services/paymentMonitor.ts

@@ -1,7 +1,7 @@
 import { ref } from 'vue'
 import { BaseService } from '@/core/base/BaseService'
 import type { PaymentStatus, LightningInvoice } from '@/core/services/invoiceService'
-import type { Order } from '@/stores/market'
+import type { Order } from '@/modules/market/stores/market'
 
 export interface PaymentMonitorState {
   isMonitoring: boolean