The header status bar read the global /api/sync/status (videos_total +
channels_backfilling), so every user saw the whole catalog's numbers —
confusing and a small cross-user info leak (e.g. "3 syncing" for a user with 2
channels). It now uses /api/sync/my-status: the user's own available video count
and how many of their own channels are still being fetched
(channels_recent_pending). The pause control stays admin-only via an isAdmin prop.