- Migrated all hooks: useAuth, useChat, useLogin
- Migrated all components: Header, ProfileForm, FollowButton, LikeButton, PlaylistFollowButton, ChatMessage, ChatMessages, CommentThread, CommentSection, PlaylistList, ChatSidebar, SettingsPage, DashboardPage
- Updated storeSelectors.ts useAuthUser() to use React Query
- All production code now uses useUser() hook instead of Zustand store
- Action 4.1.1.3 and 4.1.1.4 complete