- Add `lib/constants.ts` exporting `DATA_DIR`, `DATABASE_URL`, `CACHE_DIR`,
`BACKUP_DIR`, `AVATAR_DIR`, `TMDB_API_BASE_URL`, and `TMDB_IMAGE_BASE_URL`
- Replace inline `process.env` derivations in `db/client`, `backup`,
`image-cache`, `system-health`, `tmdb/client`, `actions/settings`,
and `api/avatars` with imports from the new module
- Add `uploadAvatarAction` and `removeAvatarAction` server actions;
store files under `DATA_DIR/avatars/{userId}.{ext}` via Bun.write
- Add `GET /api/avatars/[userId]` route that scans the avatar dir with
Bun.Glob and serves with immutable Cache-Control (cache-busted via
query param)
- Refactor AccountSection with hover overlay, AnimatePresence fade,
and file input; click avatar to upload (no image) or remove (has image)
- Replace NavBar user initial badge with Avatar + DropdownMenu showing
name, email, settings link, and sign-out
- Thread `userEmail` and `userImage` props through AuthenticatedShell
→ NavBar and SettingsPage → AccountSection
jake