docs(user): two more code-grounding fixes from the verification sweep

- sync-guide matching ladder was missing rung 8: Title only at 0.3
  confidence, last-resort after title+author+size (book_matching.go
  priorities 1-8, file-path priority handled at the API layer).
- library-browsing said the sort dropdown had 'more' options than it
  does: exactly five (Title A-Z/Z-A, Author A-Z, Date Added, Page
  Count).

Sweep results, all verified against source: themes.md 24+13=37 exact
(web/src/theme.ts union), reader-guide claims (corner zones, selection
copy, comics annotations disabled - bookmarks only) present in
web/src/reader/reader.ts, android-app.md strings (local-network
permission, login error table) in bookhoard-app source, calibre
dc:title/calibre:series parsing in media_scanner_calibre fixtures.

docs/user/sync-guide.md

@@ -40,6 +40,7 @@ by fingerprint, strongest first:
 4. **OPF identifier** — 85%
 5. **ISBN / ASIN** — 80%
 6. **Title + Author + file size** — 50%
+7. **Title only** — 30% (last resort, only tried when nothing else matched)
 
 Books that match automatically never bother you. The ones that can't
 (side-loaded files, converted formats like EPUB → KEPUB, mismatched