Initial commit: Plataforma de Economía

Features:
- React 18 + TypeScript frontend with Vite
- Go + Gin backend API
- PostgreSQL database
- JWT authentication with refresh tokens
- User management (admin panel)
- Docker containerization
- Progress tracking system
- 4 economic modules structure

Fixed:
- Login with username or email
- User creation without required email
- Database nullable timestamps
- API response field naming

.env.example

@@ -0,0 +1,12 @@
+# Database
+DB_USER=econ_user
+DB_PASSWORD=change_this_password_in_production
+DB_NAME=econ_db
+DB_HOST=localhost
+DB_PORT=5432
+
+# JWT
+JWT_SECRET=your-secret-key-change-in-production-min-32-chars
+
+# Server
+SERVER_PORT=8080