fix: require open drawer to complete transactions, fix product price field

- Backend enforces open drawer at location before completing any transaction
- Frontend disables payment buttons when drawer is closed with warning message
- Fix product price field name (price, not sellingPrice) in POS API types
- Fix seed UUIDs to use valid UUID v4 format (version nibble must be 1-8)
- Fix Vite allowedHosts for dev.lunarfront.tech access
- Add e2e test for drawer enforcement (39 POS tests now pass)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/backend/src/db/seeds/music-store-seed.ts

@@ -8,7 +8,7 @@
 import postgres from 'postgres'
 
 const DB_URL = process.env.DATABASE_URL ?? 'postgresql://lunarfront:lunarfront@localhost:5432/lunarfront'
-const COMPANY_ID = 'a0000000-0000-0000-0000-000000000001'
+const COMPANY_ID = 'a0000000-0000-4000-8000-000000000001'
 
 const sql = postgres(DB_URL)