Applied 2026-05-11 across both prod (13 users) and dev (1 user).
Replaces 'nextup' homesection slot with 'none' on every user; seeds 'resume'
at slot 0 for users whose CustomPrefs was empty (would have fallen back to
the Jellyfin factory default that includes Next Up).
Idempotent — re-running is a no-op once converged.
