test(GRO-2652): stub fetch in auth tests to fix OIDC discovery timeout flake

AbortSignal.timeout(5000) in initAuth's discovery fetch races with
vitest's 5000ms default test timeout, causing intermittent failures on CI push
runs. Stub fetch to return ok:false instantly so tests complete in <1s.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/__tests__/auth.test.ts

@@ -69,9 +69,14 @@ describe("auth init", () => {
   beforeEach(() => {
     dbSelectResult = [];
     vi.clearAllMocks();
+    // Stub fetch so OIDC discovery requests resolve instantly during tests.
+    // Without this, AbortSignal.timeout(5000) in auth.ts races with vitest's
+    // 5000ms default test timeout and causes flaky failures.
+    vi.stubGlobal("fetch", vi.fn().mockResolvedValue({ ok: false, status: 503 }));
   });
 
   afterEach(() => {
+    vi.unstubAllGlobals();
     process.env = { ...originalEnv };
   });