v0.26.1: The background jobs keep up now

The background jobs keep up now

Fingerprinting ran once, five minutes after the server started, and never again. Nothing else asked for
it either — not a library scan, not the updater sweep, not adding a series from Discover — so every chapter
downloaded after that single pass went unprocessed until the container happened to restart. A server that
simply stays up was the worst case, which is exactly backwards.

The effect was invisible because it looks like nothing: the reader treats an un-fingerprinted page as an
ordinary page, so the feature just quietly stopped applying to anything new. Measured on a real library the
day it shipped: 22 chapters, all added after that morning's boot, still untouched hours later, with 50 to 80
more arriving daily.

Both backfills now re-check every six hours, re-arming after each pass — including a pass that failed, since
a job that stops rescheduling because one batch went wrong is the same bug wearing a different hat. The long
first delay stays: page fingerprinting decodes every page in the library and should not compete with a server
that has just booted.

The same fault was in the older chapter-fingerprint job, which feeds folder rematch. Fixed alongside.

Marking a page by hand no longer switches the feature off for that chapter

Marking a page as repeated wrote a row that made the chapter look already-processed, so it was dropped from
the queue for good — its other pages were never fingerprinted and the automatic rule never ran there again.
Marking one advert turned detection off for the whole chapter, and it was most likely on a new series,
where the backlog is exactly the chapters being opened.

A chapter is now recorded as looked-at only when it has actually been looked at.

Admin → Tasks shows the backlog

The number of chapters still waiting was calculated, sent to the browser and then discarded, so a job that had
quietly stopped picking up work looked identical to one with nothing left to do. Each task now shows how many
items are outstanding, and the schedule reads honestly instead of claiming the job runs once.