feat: implement AuthModule with authentication and RBAC features

Added AuthModule with services, controllers, and guards for authentication. Implements session management, role-based access control, 2FA, and DTOs for user login, registration, and token refresh.

backend/src/auth/dto/refresh.dto.ts

@@ -0,0 +1,7 @@
+import { IsNotEmpty, IsString } from "class-validator";
+
+export class RefreshDto {
+	@IsString()
+	@IsNotEmpty()
+	refresh_token!: string;
+}