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/dev-seed.ts

@@ -7,7 +7,7 @@
 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)
 
@@ -18,7 +18,7 @@ async function seed() {
   const [company] = await sql`SELECT id FROM company WHERE id = ${COMPANY_ID}`
   if (!company) {
     await sql`INSERT INTO company (id, name, timezone) VALUES (${COMPANY_ID}, 'Demo Store', 'America/Chicago')`
-    await sql`INSERT INTO location (id, name) VALUES ('a0000000-0000-0000-0000-000000000002', 'Main Store')`
+    await sql`INSERT INTO location (id, name, tax_rate, service_tax_rate) VALUES ('a0000000-0000-4000-8000-000000000002', 'Main Store', '0.0825', '0.0825')`
     console.log('  Created company and location')
 
     // Seed RBAC

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)