Stats panel: a persistent spinner marks whichever target is currently
being scanned/reacted to, and jittered waits show a live-ticking
countdown bar instead of a static "waiting Xs" line. Both the status
line and countdown row are always rendered (blank when idle) so their
appearing/disappearing no longer shifts the table's height.
Backlog: channel_scan_state now tracks oldest_covered_at alongside
newest_id_seen. If days_back is widened after a channel already has a
resume checkpoint, the forward-only diff would never look back far
enough to notice — now the newly-exposed gap gets backfilled first.
Minz
ef90ee6a0b