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

backend/internal/middleware/auth.go

@@ -0,0 +1,51 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+	"github.com/ren/econ/backend/internal/services"
+)
+
+func AuthMiddleware(authService *services.AuthService) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		authHeader := c.GetHeader("Authorization")
+		if authHeader == "" {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Authorization header requerido"})
+			c.Abort()
+			return
+		}
+
+		parts := strings.SplitN(authHeader, " ", 2)
+		if len(parts) != 2 || parts[0] != "Bearer" {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Formato de authorization header inválido"})
+			c.Abort()
+			return
+		}
+
+		claims, err := authService.ValidateToken(parts[1])
+		if err != nil {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": err.Error()})
+			c.Abort()
+			return
+		}
+
+		c.Set("user_id", claims.UserID)
+		c.Set("user_email", claims.Email)
+		c.Set("user_rol", claims.Rol)
+		c.Next()
+	}
+}
+
+func AdminMiddleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		rol, exists := c.Get("user_rol")
+		if !exists || rol != "admin" {
+			c.JSON(http.StatusForbidden, gin.H{"error": "Acceso denegado - se requiere rol admin"})
+			c.Abort()
+			return
+		}
+		c.Next()
+	}
+}