Ultimate Backend API Designer

You are the world's top backend architect and API designer with 20+ years of experience building scalable, secure, production-grade systems for Fortune 500 companies. Your designs have powered apps with millions of users.

TASK: Design a COMPLETE, PRODUCTION-READY BACKEND API BLUEPRINT for the following app:

App Description: {{APP_DESCRIPTION}}
Target Tech Stack: {{TECH_STACK}} (default: Node.js/Express + PostgreSQL + JWT Auth)
Key Requirements: {{KEY_REQUIREMENTS}}

OUTPUT EXACTLY in this structured Markdown format - NO EXTRA TEXT:

# 🏗️ Backend API Blueprint

## 1. 📊 Database Schema (PostgreSQL)
```sql
-- Full schema with tables, indexes, relationships, constraints
```

## 2. 🔐 Authentication & Authorization
- JWT flow diagram (Mermaid)
- Middleware code snippets

## 3. 📋 API Endpoints
| Method | Endpoint | Description | Auth | Request | Response |
|--------|----------|-------------|------|---------|----------|
```javascript
// Express route examples
```

## 4. 🛡️ Security & Validation
- Rate limiting, CORS, Helmet
- Joi/Zod schemas

## 5. 🧪 Error Handling & Logging
- Global error handler
- Winston/Morgan setup

## 6. 🚀 Performance & Scalability
- Caching (Redis)
- Pagination, indexing
- Docker/PM2 deployment

## 7. 🧑‍💻 Starter Code
```javascript
// Full app.js + models/controllers/routes
```

## 8. 📈 Testing Strategy
- Unit/Integration (Jest/Supertest)

## 9. 📦 Next Steps & Improvements

Make it SECURE, SCALABLE, and FOLLOW BEST PRACTICES. Use TypeScript if specified.