chore: initial project scaffold with admin web, backend, desktop client, and deployment setup

Add monorepo structure for NexaVPN WireGuard control plane including:
- .gitignore for node_modules, build artifacts, and environment files
- README with project overview, monorepo layout, and quick start guide
- Admin web UI with React, Vite, TypeScript, and nginx reverse proxy
- API client with type definitions for users, devices, policies, gateways, and audit logs
- Admin pages for dashboard, users, devices, policies, g

backend/internal/user/repository.go

@@ -0,0 +1,64 @@
+package user
+
+import (
+	"context"
+
+	"github.com/google/uuid"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type Repository interface {
+	List(ctx context.Context) ([]User, error)
+	Create(ctx context.Context, input CreateRequest, passwordHash string) (User, error)
+	SetActive(ctx context.Context, userID uuid.UUID, active bool) error
+}
+
+type PGRepository struct {
+	db *pgxpool.Pool
+}
+
+func NewPGRepository(db *pgxpool.Pool) *PGRepository {
+	return &PGRepository{db: db}
+}
+
+func (r *PGRepository) List(ctx context.Context) ([]User, error) {
+	rows, err := r.db.Query(ctx, `
+		select u.id, r.id, r.name, u.username, u.display_name, coalesce(u.email, ''), u.is_active
+		from users u
+		join roles r on r.id = u.role_id
+		where u.deleted_at is null
+		order by u.created_at desc
+	`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var users []User
+	for rows.Next() {
+		var item User
+		if err := rows.Scan(&item.ID, &item.RoleID, &item.RoleName, &item.Username, &item.DisplayName, &item.Email, &item.IsActive); err != nil {
+			return nil, err
+		}
+		users = append(users, item)
+	}
+	return users, rows.Err()
+}
+
+func (r *PGRepository) Create(ctx context.Context, input CreateRequest, passwordHash string) (User, error) {
+	const query = `
+		insert into users (id, role_id, username, display_name, email, password_hash)
+		values ($1, (select id from roles where name = $2), $3, $4, nullif($5, ''), $6)
+		returning id, username, display_name, coalesce(email, ''), is_active
+	`
+
+	item := User{RoleName: input.Role}
+	err := r.db.QueryRow(ctx, query, uuid.New(), input.Role, input.Username, input.DisplayName, input.Email, passwordHash).
+		Scan(&item.ID, &item.Username, &item.DisplayName, &item.Email, &item.IsActive)
+	return item, err
+}
+
+func (r *PGRepository) SetActive(ctx context.Context, userID uuid.UUID, active bool) error {
+	_, err := r.db.Exec(ctx, `update users set is_active = $2, updated_at = now() where id = $1`, userID, active)
+	return err
+}