Revert: Move VueFire persistence configuration to initialization (#5614) (#5729)

## Summary
This reverts PR #5614 which moved VueFire persistence configuration to
initialization.

## Reason for Revert

It breaks Google SSO login with error:

```
useErrorHandling.ts:12 FirebaseError: Firebase: Error (auth/argument-error).
    at createErrorInternal (index-c92d61ad.js:506:41)
    at _assert (index-c92d61ad.js:512:15)
    at _withDefaultResolver (index-c92d61ad.js:9237:5)
    at signInWithPopup (index-c92d61ad.js:9457:30)
    at executeAuthAction.createCustomer (firebaseAuthStore.ts:263:25)
    at executeAuthAction (firebaseAuthStore.ts:223:28)
    at Proxy.loginWithGoogle (firebaseAuthStore.ts:262:5)
    at Proxy.wrappedAction (pinia.mjs:1405:26)
    at useFirebaseAuthActions.ts:104:28
    at Object.signInWithGoogle (useErrorHandling.ts:39:22)
```

## Changes
- Reverts commit ea4e57b60 "Move VueFire persistence configuration to
initialization (#5614)"
- Restores previous Firebase auth persistence behavior

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5729-Revert-Move-VueFire-persistence-configuration-to-initialization-5614-2776d73d3650814c9b80d9c67c852874)
by [Unito](https://www.unito.io)

src/stores/firebaseAuthStore.ts

@@ -6,10 +6,12 @@ import {
   GoogleAuthProvider,
   type User,
   type UserCredential,
+  browserLocalPersistence,
   createUserWithEmailAndPassword,
   deleteUser,
   onAuthStateChanged,
   sendPasswordResetEmail,
+  setPersistence,
   signInWithEmailAndPassword,
   signInWithPopup,
   signOut,
@@ -80,6 +82,8 @@ export const useFirebaseAuthStore = defineStore('firebaseAuth', () => {
   // Retrieves the Firebase Auth instance. Returns `null` on the server.
   // When using this function on the client in TypeScript, you can force the type with `useFirebaseAuth()!`.
   const auth = useFirebaseAuth()!
+  // Set persistence to localStorage (works in both browser and Electron)
+  void setPersistence(auth, browserLocalPersistence)
 
   onAuthStateChanged(auth, (user) => {
     currentUser.value = user