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/App.test.jsx

@@ -588,14 +588,17 @@ describe('Home page', () => {
     expect(JSON.parse(localStorage.getItem('bible-study-index'))[0].title).toBe('Titus Deep Dive');
   });
 
-  test('deleting a project removes it after confirmation', async () => {
+  test('deleting a project removes it at once, and Undo brings it back', async () => {
     seedProject();
-    window.confirm.mockReturnValue(true);
     const user = userEvent.setup();
     await renderApp();
     await user.click(screen.getByRole('button', { name: /^delete$/i }));
     await waitFor(() => expect(screen.queryByText('Titus Notes')).not.toBeInTheDocument());
     expect(localStorage.getItem('bible-study-project-p1')).toBeNull();
+    expect(window.confirm).not.toHaveBeenCalled();
+    await user.click(await screen.findByRole('button', { name: /undo/i }));
+    expect(await screen.findByText('Titus Notes')).toBeInTheDocument();
+    expect(localStorage.getItem('bible-study-project-p1')).not.toBeNull();
   });
 
   test('sort choice is remembered after leaving Home', async () => {
@@ -760,28 +763,28 @@ describe('Chunk builder', () => {
     expect(await addSecondChapter(user)).toHaveAttribute('aria-current', 'true');
   });
 
-  test('the Outline stage reopens the chapter of the chunk being studied', async () => {
+  test('the Chunks stage reopens the chapter of the chunk being studied', async () => {
     const user = await loadChapter();
     await addSecondChapter(user);
     addChunk('Paul, a servant', 'In hope of eternal'); // chunk in Titus 2 (now selected)
     await user.click(screen.getByRole('button', { name: 'Titus 1' }));
     await user.click(screen.getByRole('button', { name: /begin studying/i }));
     await findChunkCounter(1, 1);
-    await user.click(screen.getByRole('button', { name: /^outline$/i }));
+    await user.click(screen.getByRole('button', { name: /^chunks$/i }));
     expect(await screen.findByRole('button', { name: 'Titus 2' })).toHaveAttribute('aria-current', 'true');
   });
 });
 
 // ---------------------------------------------------------------------------
-// Stage bar (Outline / Study / Script / Export)
+// Stage bar (Chunks / Study / Outline / Script / Export)
 // ---------------------------------------------------------------------------
 describe('Stage bar', () => {
   test('later stages are disabled until a chunk exists', async () => {
     await loadChapter();
-    for (const name of [/^study$/i, /^script$/i, /^export$/i]) {
+    for (const name of [/^study$/i, /^outline$/i, /^script$/i, /^export$/i]) {
       expect(screen.getByRole('button', { name })).toBeDisabled();
     }
-    expect(screen.getByRole('button', { name: /^outline$/i })).not.toBeDisabled();
+    expect(screen.getByRole('button', { name: /^chunks$/i })).not.toBeDisabled();
     addChunk('Paul, a servant', 'Paul, a servant');
     await screen.findByText('1 created');
     expect(screen.getByRole('button', { name: /^study$/i })).not.toBeDisabled();
@@ -1240,7 +1243,7 @@ describe('Back to the dashboard', () => {
     await dashboard();
   });
 
-  test.each(['Outline', 'Study', 'Script', 'Export'])('the %s stage of a study', async (stage) => {
+  test.each(['Chunks', 'Study', 'Outline', 'Script', 'Export'])('the %s stage of a study', async (stage) => {
     const u = await loadChapter();
     addChunk('Paul, a servant', 'In hope of eternal');
     await screen.findByText('1 created');
@@ -1431,7 +1434,7 @@ describe('New pages start at the top', () => {
     await screen.findByRole('heading', { name: /^reading plans$/i });
     expect(scroller.scrollTop).toBe(0);
     scroller.scrollTop = 300;
-    await user.click(screen.getByRole('button', { name: /back to home/i }));
+    await user.click(screen.getByRole('button', { name: /back to home|bible study home/i }));
     await screen.findByText('My Studies');
     expect(scroller.scrollTop).toBe(0);
   });