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>

frontend/Dockerfile

@@ -0,0 +1,12 @@
+FROM node:20-alpine AS build
+WORKDIR /app
+COPY package*.json ./
+RUN npm install
+COPY . .
+RUN npm run build
+
+FROM nginx:alpine
+COPY --from=build /app/dist /usr/share/nginx/html
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+EXPOSE 80
+CMD ["nginx", "-g", "daemon off;"]