Make the app work better on iPhone and iPad

- Text fields are at least 16px on touch screens (stops iOS zooming on focus)
- Chapter swipe ignores sheets, fields, sliders, sideways-scrolling rows and text selection
- vh -> dvh for sheets, palette and dialogs
- Bigger tap targets for small links, chips and the logo; no double-tap delay
- No tap flash or landscape text inflation

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

src/components/study/PageShell.jsx

@@ -70,7 +70,7 @@ export default function PageShell({ title, onBack, actions, active = null, maxWi
       <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-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">
+          <button type="button" onClick={goHome} className="-m-2 flex shrink-0 items-center gap-2 p-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>