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>

src/utils/exportBuilders.js

@@ -4,6 +4,7 @@ import {
   getChunkVerseEntries,
   htmlToPlainText,
 } from './bibleUtils.jsx';
+import { outlineToMarkdown } from './outline.js';
 
 // ---------------------------------------------------------------------------
 // Export / prompt builders (exported for testing)
@@ -48,7 +49,8 @@ export function buildMarkdownExport(project) {
     return `## ${ch.book} ${ch.chapter}\n\n${chunkSections}`;
   }).join('\n');
 
-  return `# ${project.title}\n\n*${project.translation}*\n\n${chapterSections}`;
+  const outline = (project.outline ?? []).length > 0 ? `## Outline\n\n${outlineToMarkdown(project.outline)}\n\n` : '';
+  return `# ${project.title}\n\n*${project.translation}*\n\n${outline}${chapterSections}`;
 }
 
 export function buildChunkBodies(project) {