Add Outline stage, parallel reading, offline saves, backup, sync-conflict handling and more

Study
- New Outline stage (hierarchical I./A./1. points, linked to chunks, in all exports);
  the chunk stage is now "Chunks"
- Home cards: passages shown as ranges, tags capped with "+N more"

Reader
- Side-by-side translations and a Compare tab per verse
- Typeface, line spacing, verse-number settings; text and column scale with the screen
- Highlights/bookmarks sheet with named colours (synced); BSB footnote spacing fix
- Cmd-K palette (passages, studies, notes, marks), keyboard shortcuts and "?" help

Flow and safety
- Toasts with Undo replace most confirm()/alert()
- Back/Forward move between pages
- Server refuses saves over a newer copy (409); keep-mine / use-other banner;
  opening a study no longer re-stamps it
- Latest chapter request wins when flipping quickly

Offline and data
- Save books, plan days or a whole BSB/NET for offline
- Service worker fixes: helloao /api/ URLs were skipped and responses cloned too late
- Settings: download/restore a full backup

Accessibility
- Sheets trap focus and close on Escape, skip link, focus ring, reduced motion,
  theme contrast raised to 4.5:1 (with a test)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/readerMarks.js

@@ -30,10 +30,13 @@ export function cleanMarks(body) {
       if (!int(h.startOffset, 0, 5000) || !int(h.endOffset, 1, 5000) || h.endOffset <= h.startOffset) continue;
       if (typeof h.color !== 'string' || !COLOR.test(h.color)) continue;
       seen.add(h.id);
-      highlights.push({
+      const entry = {
         id: h.id, book: String(h.book).toUpperCase(), chapter: h.chapter, verse: h.verse,
         startOffset: h.startOffset, endOffset: h.endOffset, color: h.color,
-      });
+      };
+      // The highlighted words, kept so lists of highlights can show them without loading the chapter
+      if (typeof h.text === 'string' && h.text.length > 0) entry.text = h.text.slice(0, 500);
+      highlights.push(entry);
     }
   }
   return { bookmarks, highlights };