test(auth): add comment to clarify DTO usage in register test

backend/src/auth/auth.controller.spec.ts

@@ -75,6 +75,7 @@ describe("AuthController", () => {
 				password: "password",
 				username: "test",
 			};
+			// biome-ignore lint/suspicious/noExplicitAny: Necessary to avoid defining full DTO in test
 			await controller.register(dto as any);
 			expect(authService.register).toHaveBeenCalledWith(dto);
 		});