Three small items from the earlier audit pass:

1. README — status checklist was stale (only listed sign-in and
   token refresh); now reflects the feeds, detail, bookmarks, search,
   muting, and iPad-ergonomics work that's actually shipped. Also adds
   the explicit "no App Store, personal use only" scope note and a
   "Nuke is linked via project.pbxproj, no Package.swift" line so a
   contributor doesn't waste time chasing SPM setup.

2. TTLDataCache — add a comment above @unchecked Sendable explaining
   that `timestamps` is serialized by NSLock. The conformance is safe
   but easy to mis-read; the comment tells a future reader not to
   introduce un-locked accesses.

3. IllustFeedViewModel.prefetchDistance — existing docstring said WHAT
   the field does ("higher = more aggressive"). Add a WHY line for the
   default of 6: ~600pt lookahead at typical cell heights, tuned so
   normal scroll momentum lands a page without paginating eagerly when
   the user is idling near the bottom.

No behavior change.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>