[test] Fix axios mocking in firebaseAuthStore tests

Use vi.mock() with factory function to ensure axios mock is set up before module imports. This fixes test failures caused by the store creating axios client at module level.

Fixes test execution in CI

tests-ui/tests/store/firebaseAuthStore.test.ts

@@ -7,23 +7,28 @@ import * as vuefire from 'vuefire'
 import { useFirebaseAuthStore } from '@/stores/firebaseAuthStore'
 
 // Mock axios before any imports that use it
-vi.mock('axios')
+vi.mock('axios', () => {
+  const mockAxiosInstance = {
+    get: vi.fn().mockResolvedValue({
+      data: { balance: { credits: 0 } },
+      status: 200
+    }),
+    post: vi.fn().mockResolvedValue({
+      data: { id: 'test-customer-id' },
+      status: 201
+    })
+  }
+
+  return {
+    default: {
+      create: vi.fn().mockReturnValue(mockAxiosInstance),
+      isAxiosError: vi.fn().mockImplementation(() => false)
+    }
+  }
+})
+
 const mockedAxios = vi.mocked(axios)
-
-// Set up axios mock with default instance
-const mockAxiosInstance = {
-  get: vi.fn().mockResolvedValue({
-    data: { balance: { credits: 0 } },
-    status: 200
-  }),
-  post: vi.fn().mockResolvedValue({
-    data: { id: 'test-customer-id' },
-    status: 201
-  })
-}
-
-mockedAxios.create = vi.fn().mockReturnValue(mockAxiosInstance)
-mockedAxios.isAxiosError = vi.fn().mockImplementation(() => false) as any
+const mockAxiosInstance = mockedAxios.create() as any
 
 // Mock fetch
 const mockFetch = vi.fn()
@@ -122,7 +127,7 @@ describe('useFirebaseAuthStore', () => {
       data: { id: 'test-customer-id' },
       status: 201
     })
-    mockedAxios.isAxiosError = vi.fn().mockImplementation(() => false) as any
+    ;(mockedAxios.isAxiosError as any).mockReturnValue(false)
 
     // Mock useFirebaseAuth to return our mock auth object
     vi.mocked(vuefire.useFirebaseAuth).mockReturnValue(mockAuth as any)