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/pages/SettingsPage.jsx

@@ -1,7 +1,8 @@
-import { useState } from 'react';
+import { useEffect, useState } from 'react';
 import { useApp } from '../context/AppContext.js';
 import PageShell from '../components/study/PageShell.jsx';
-import { READER_TRANSLATIONS } from '../hooks/useBibleReader.js';
+import { READER_TRANSLATIONS } from '../utils/bibleText.js';
+import DataSection from '../components/settings/DataSection.jsx';
 import { COMMENTARIES } from '../hooks/useVerseStudy.js';
 import { READER_THEMES } from '../components/reader/readerThemes.js';
 import {
@@ -55,7 +56,15 @@ export default function SettingsPage() {
     readerWide, setReaderWide,
     readerCommentary, setReaderCommentary,
     audioNarrator, setAudioNarrator,
+    settingsFocus, clearSettingsFocus,
   } = useApp();
+
+  // "Back up my data" from the ⌘K palette lands on that section
+  useEffect(() => {
+    if (!settingsFocus) return;
+    document.getElementById(settingsFocus)?.scrollIntoView({ block: 'start' });
+    clearSettingsFocus();
+  }, [settingsFocus]); // eslint-disable-line react-hooks/exhaustive-deps
   const [mfaSetup, setMfaSetup] = useState(null); // { secret, qrCodeDataUrl } while setup is in progress
   const [mfaSetupCode, setMfaSetupCode] = useState('');
   const [mfaSetupError, setMfaSetupError] = useState('');
@@ -341,6 +350,8 @@ export default function SettingsPage() {
           {podcastNameSaved && <p className="text-sm text-[var(--r-accent)]">Saved.</p>}
         </section>
 
+        <DataSection />
+
         <section className="rounded-2xl border border-[var(--r-line)] bg-[var(--r-bar)] p-6 space-y-4">
           <div>
             <h2 className="text-base font-medium text-[var(--r-text)]">My reading journal</h2>