Refactors the AuthProvider component in `src/hooks/useAuth.tsx` to properly export the component, addressing Fast Refresh compatibility warnings and improving developer experience.
Replit-Commit-Author: Agent
Replit-Commit-Session-Id: fe5b902e-beda-40fc-bf87-a3c4ab300e3a
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replaces `previousEmail` state with a ref (`previousEmailRef`) to accurately track the user's old email address during authentication flow, specifically for handling email change notifications.
Replit-Commit-Author: Agent
Replit-Commit-Session-Id: a16cce43-1d93-4e5c-a1e6-6ca90e68cc4f
Replit-Commit-Checkpoint-Type: full_checkpoint