The series hero CTA chose its verb from a whole-list `anyRead` check, so a
volume partially read (e.g. 18%) — whose read flag is still false — fell
through to "Start Reading" even though the resume target already had
reading progress. A later volume read out of order would also mislabel an
in-progress earlier volume as "Continue".
Add resumeState() to the manga chapter library: it walks the flat reading
order once to resolve the resume target, derives "earlier read" only from
chapters before the target (so skip-ahead / manual mark-read doesn't flip
the verb), and flags the target as in-progress only for a reading position
strictly inside (0, 1) — the server marks a chapter read past its finished
threshold, so a full-progress target with a stale read flag must not show
"Resume Reading". The CTA verb is now hasEarlierRead ? "Continue"
: targetInProgress ? "Resume Reading" : "Start Reading"; a pristine series
still shows "Start Reading" and a fully read one "Read Again".
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
