feat: ESP32 DIY platform Phase 1 — marketplace with mock payment & flash token flow

- React+Vite frontend (dark theme, role-based routing: admin/seller/buyer)
- Express+Prisma+PostgreSQL backend with JWT auth and audit logging
- MinIO object storage with backend proxy for CORS-free firmware delivery
- Mock payment flow (order → mock-pay → FlashToken) for pre-business testing
- FlashToken lifecycle: issue → validate → esp-web-tools manifest → consume
- Admin approval workflow for project/product submissions
- Toss Payments integration guide (TOSS_PAYMENT_GUIDE.md) for live keys

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/package.json

@@ -0,0 +1,32 @@
+{
+  "name": "platform-backend",
+  "version": "1.0.0",
+  "type": "commonjs",
+  "scripts": {
+    "start": "node src/index.js",
+    "dev": "nodemon src/index.js",
+    "db:migrate": "prisma migrate deploy",
+    "db:generate": "prisma generate",
+    "db:push": "prisma db push",
+    "postinstall": "prisma generate"
+  },
+  "dependencies": {
+    "@prisma/client": "^5.14.0",
+    "bcryptjs": "^2.4.3",
+    "cors": "^2.8.5",
+    "express": "^4.19.2",
+    "express-rate-limit": "^7.3.1",
+    "express-validator": "^7.1.0",
+    "helmet": "^7.1.0",
+    "ioredis": "^5.4.1",
+    "jsonwebtoken": "^9.0.2",
+    "minio": "^8.0.0",
+    "multer": "^1.4.5-lts.1",
+    "sharp": "^0.33.4",
+    "uuid": "^10.0.0"
+  },
+  "devDependencies": {
+    "nodemon": "^3.1.4",
+    "prisma": "^5.14.0"
+  }
+}