test(frontend): simplify fetch mock signatures in auth tests

frontend/src/main.test.ts

@@ -440,7 +440,7 @@ describe("auth and user list wiring", () => {
   it("logs in and updates the auth UI", async () => {
     await import("../src/main");
 
-    globalThis.fetch = vi.fn(async (url: any, opts?: any) => {
+    globalThis.fetch = vi.fn(async (url: any) => {
       const u = String(url);
       if (u.includes("/api/auth/login")) {
         return {
@@ -470,9 +470,7 @@ describe("auth and user list wiring", () => {
   it("toggles the user list visibility", async () => {
     await import("../src/main");
 
-    globalThis.fetch = vi
+    globalThis.fetch = vi.fn().mockResolvedValue({
-      .fn()
-      .mockResolvedValue({
       ok: true,
       json: async () => ({ authenticated: false, entries: [] }),
       text: async () => "",