Move VueFire persistence configuration to initialization (#5614)

Currently, we set persistence method in the auth store setup. This
creates pattern of using the default on init (indexed DB) up until the
firebase store is initialized and `setPersistence` is called. For
devices that don't support indexed DB or have the connection aggresively
terminated or cleared, like
[Safari](https://comfy-org.sentry.io/issues/6879071102/?project=4509681221369857&query=is%3Aunresolved&referrer=issue-stream),
this can create problems with maintaing auth persistence.

Fix by setting persistence method in the initialization in main.ts

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5614-Move-VueFire-persistence-configuration-to-initialization-2716d73d3650817480e0c8feb1f37b9a)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude <noreply@anthropic.com>

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

@@ -148,13 +148,6 @@ describe('useFirebaseAuthStore', () => {
     expect(store.loading).toBe(false)
   })
 
-  it('should set persistence to local storage on initialization', () => {
-    expect(firebaseAuth.setPersistence).toHaveBeenCalledWith(
-      mockAuth,
-      firebaseAuth.browserLocalPersistence
-    )
-  })
-
   it('should properly clean up error state between operations', async () => {
     // First, cause an error
     const mockError = new Error('Invalid password')