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/repository/user.go

@@ -0,0 +1,128 @@
+package repository
+
+import (
+	"context"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/jackc/pgx/v5/pgxpool"
+	"github.com/ren/econ/backend/internal/models"
+)
+
+type UserRepository struct {
+	db *pgxpool.Pool
+}
+
+func NewUserRepository(db *pgxpool.Pool) *UserRepository {
+	return &UserRepository{db: db}
+}
+
+func (r *UserRepository) Create(ctx context.Context, user *models.Usuario) error {
+	user.ID = uuid.New()
+	user.CreadoEn = time.Now()
+	user.Activo = true
+	if user.Rol == "" {
+		user.Rol = "estudiante"
+	}
+
+	query := `
+		INSERT INTO usuarios (id, email, username, password_hash, nombre, rol, creado_en, activo)
+		VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
+	`
+	_, err := r.db.Exec(ctx, query,
+		user.ID, user.Email, user.Username, user.PasswordHash, user.Nombre, user.Rol, user.CreadoEn, user.Activo)
+	return err
+}
+
+func (r *UserRepository) GetByID(ctx context.Context, id uuid.UUID) (*models.Usuario, error) {
+	query := `
+		SELECT id, email, username, password_hash, nombre, rol, creado_en, ultimo_login, activo
+		FROM usuarios WHERE id = $1
+	`
+	var user models.Usuario
+	err := r.db.QueryRow(ctx, query, id).Scan(
+		&user.ID, &user.Email, &user.Username, &user.PasswordHash, &user.Nombre,
+		&user.Rol, &user.CreadoEn, &user.UltimoLogin, &user.Activo)
+	if err != nil {
+		return nil, err
+	}
+	return &user, nil
+}
+
+func (r *UserRepository) GetByEmail(ctx context.Context, email string) (*models.Usuario, error) {
+	query := `
+		SELECT id, email, username, password_hash, nombre, rol, creado_en, ultimo_login, activo
+		FROM usuarios WHERE email = $1
+	`
+	var user models.Usuario
+	err := r.db.QueryRow(ctx, query, email).Scan(
+		&user.ID, &user.Email, &user.Username, &user.PasswordHash, &user.Nombre,
+		&user.Rol, &user.CreadoEn, &user.UltimoLogin, &user.Activo)
+	if err != nil {
+		return nil, err
+	}
+	return &user, nil
+}
+
+func (r *UserRepository) GetByUsername(ctx context.Context, username string) (*models.Usuario, error) {
+	query := `
+		SELECT id, email, username, password_hash, nombre, rol, creado_en, ultimo_login, activo
+		FROM usuarios WHERE username = $1
+	`
+	var user models.Usuario
+	err := r.db.QueryRow(ctx, query, username).Scan(
+		&user.ID, &user.Email, &user.Username, &user.PasswordHash, &user.Nombre,
+		&user.Rol, &user.CreadoEn, &user.UltimoLogin, &user.Activo)
+	if err != nil {
+		return nil, err
+	}
+	return &user, nil
+}
+
+func (r *UserRepository) List(ctx context.Context) ([]models.Usuario, error) {
+	query := `
+		SELECT id, email, username, password_hash, nombre, rol, creado_en, ultimo_login, activo
+		FROM usuarios ORDER BY creado_en DESC
+	`
+	rows, err := r.db.Query(ctx, query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var users []models.Usuario
+	for rows.Next() {
+		var user models.Usuario
+		err := rows.Scan(
+			&user.ID, &user.Email, &user.Username, &user.PasswordHash, &user.Nombre,
+			&user.Rol, &user.CreadoEn, &user.UltimoLogin, &user.Activo)
+		if err != nil {
+			return nil, err
+		}
+		users = append(users, user)
+	}
+	return users, nil
+}
+
+func (r *UserRepository) Update(ctx context.Context, user *models.Usuario) error {
+	query := `
+		UPDATE usuarios SET email = $2, nombre = $3, rol = $4, activo = $5
+		WHERE id = $1
+	`
+	_, err := r.db.Exec(ctx, query,
+		user.ID, user.Email, user.Nombre, user.Rol, user.Activo)
+	return err
+}
+
+func (r *UserRepository) Delete(ctx context.Context, id uuid.UUID) error {
+	// Soft delete - set activo to false
+	query := `UPDATE usuarios SET activo = false WHERE id = $1`
+	_, err := r.db.Exec(ctx, query, id)
+	return err
+}
+
+func (r *UserRepository) UpdateLastLogin(ctx context.Context, id uuid.UUID) error {
+	query := `UPDATE usuarios SET ultimo_login = $2 WHERE id = $1`
+	_, err := r.db.Exec(ctx, query, id, time.Now())
+	return err
+}