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/components/study/PageShell.jsx

@@ -3,12 +3,13 @@
 import { useEffect, useRef, useState } from 'react';
 import { useApp } from '../../context/AppContext.js';
 import { themeVars, READER_THEMES } from '../reader/readerThemes.js';
-import { ChevronLeft } from '../reader/icons.jsx';
+import { ChevronLeft, SearchIcon } from '../reader/icons.jsx';
 
+// `short` is what a phone shows; the full label is still the button's accessible name.
 const NAV = [
-  { id: 'studies', label: 'Studies' },
-  { id: 'reader', label: 'Read Bible' },
-  { id: 'plans', label: 'Reading Plans' },
+  { id: 'studies', label: 'Studies', short: 'Studies' },
+  { id: 'reader', label: 'Read Bible', short: 'Bible' },
+  { id: 'plans', label: 'Reading Plans', short: 'Plans' },
 ];
 
 // Avatar button with a dropdown: who you are, the theme, Settings, Admin, Log out.
@@ -61,25 +62,37 @@ function AccountMenu() {
 }
 
 export default function PageShell({ title, onBack, actions, active = null, maxWidth = 'max-w-6xl', children }) {
-  const { readerTheme, goHome, goStudies, openBibleReader, openReadingPlans } = useApp();
+  const { readerTheme, goHome, goStudies, openBibleReader, openReadingPlans, openPalette } = useApp();
   const go = { studies: goStudies, reader: openBibleReader, plans: openReadingPlans };
   return (
     <div className="min-h-dvh bg-[var(--r-bg)] font-sans text-[var(--r-text)]" style={themeVars(readerTheme)}>
+      <a href="#content" className="skip-link">Skip to content</a>
       <header className="safe-top sticky top-0 z-30 border-b border-[var(--r-line)] bg-[var(--r-bar)]">
-        <div className={`mx-auto flex h-12 ${maxWidth} items-center gap-4 px-4`}>
+        <div className={`mx-auto flex h-12 ${maxWidth} items-center gap-2 px-3 sm:gap-4 sm:px-4`}>
           <button type="button" onClick={goHome} className="flex shrink-0 items-center gap-2" aria-label="Bible Study home">
             <img src="/logo.svg" alt="" className="h-6 w-6" />
             <span className="hidden text-sm font-medium sm:inline">Bible Study</span>
           </button>
           <nav aria-label="Main" className="flex items-center gap-0.5">
             {NAV.map((n) => (
-              <button key={n.id} type="button" onClick={go[n.id]} aria-current={active === n.id ? 'page' : undefined}
-                className={`rounded-full px-3 py-1.5 text-sm ${active === n.id ? 'bg-[var(--r-text)] text-[var(--r-bg)]' : 'text-[var(--r-sub)] hover:bg-black/5'}`}>{n.label}</button>
+              <button key={n.id} type="button" onClick={go[n.id]} aria-current={active === n.id ? 'page' : undefined} aria-label={n.label}
+                className={`whitespace-nowrap rounded-full px-2.5 py-1.5 text-sm sm:px-3 ${active === n.id ? 'bg-[var(--r-text)] text-[var(--r-bg)]' : 'text-[var(--r-sub)] hover:bg-black/5'}`}>
+                <span className="sm:hidden" aria-hidden="true">{n.short}</span><span className="hidden sm:inline" aria-hidden="true">{n.label}</span>
+              </button>
             ))}
           </nav>
-          <div className="ml-auto"><AccountMenu /></div>
+          <div className="ml-auto flex items-center gap-2">
+            {openPalette && (
+              <button type="button" onClick={openPalette} aria-label="Search and go to"
+                className="flex items-center gap-2 rounded-full border border-[var(--r-line)] bg-[var(--r-bg)] px-3 py-1 text-xs text-[var(--r-sub)] hover:bg-black/5">
+                <SearchIcon /><span className="hidden sm:inline">Search</span><kbd className="hidden rounded border border-[var(--r-line)] px-1 text-[10px] md:inline">⌘K</kbd>
+              </button>
+            )}
+            <AccountMenu />
+          </div>
         </div>
       </header>
+      <div id="content" tabIndex={-1} className="focus:outline-none">
       <div className={`mx-auto flex ${maxWidth} flex-wrap items-center gap-3 px-4 pt-6`}>
         {onBack && (
           <button type="button" onClick={onBack} aria-label="Back" className="-ml-2 flex h-9 w-9 items-center justify-center rounded-lg text-[var(--r-sub)] hover:bg-black/5"><ChevronLeft /></button>
@@ -88,6 +101,7 @@ export default function PageShell({ title, onBack, actions, active = null, maxWi
         {actions && <div className="ml-auto flex flex-wrap items-center gap-2">{actions}</div>}
       </div>
       {children}
+      </div>
     </div>
   );
 }