- signOut() cleared the cookie but never navigated, leaving the user
stuck on the current page — redirect to /login on success.
- better-auth's core "image" field had no matching Drizzle column
(schema uses avatarUrl), so every OAuth signup threw
BetterAuthError: unable_to_create_user, silently failing before a
session was ever created. Remap via user.fields.image.
Nav links were `hidden md:flex` with no mobile fallback — sub-768px
viewports showed only logo + avatar, no way to reach Explore, Feed,
Collections, etc. Add a Sheet-based hamburger menu with the same links.
Arnaud