refactor(auth): rename id to uuid in AuthStatus and mock uuid in tests

backend/src/auth/auth.service.spec.ts

@@ -1,3 +1,7 @@
+jest.mock("uuid", () => ({
+	v4: jest.fn(() => "mocked-uuid"),
+}));
+
 import { Test, TestingModule } from "@nestjs/testing";
 
 jest.mock("@noble/post-quantum/ml-kem.js", () => ({

frontend/src/types/auth.ts

@@ -13,7 +13,7 @@ export interface RegisterPayload {
 export interface AuthStatus {
 	isAuthenticated: boolean;
 	user: null | {
-		id: string;
+		uuid: string;
 		username: string;
 		displayName?: string;
 		avatarUrl?: string;