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/CommandPalette.jsx

@@ -94,7 +94,7 @@ export default function CommandPalette({ onClose }) {
   if (authUser === null && !authServerDown) return null; // the sign-in screen has nothing to search
   let lastGroup = null;
   return (
-    <div style={themeVars(readerTheme)} className="fixed inset-0 z-[90] flex items-start justify-center bg-black/40 px-3 pt-[12vh] font-sans" onMouseDown={(e) => { if (e.target === e.currentTarget) onClose(); }}>
+    <div style={themeVars(readerTheme)} className="fixed inset-0 z-[90] flex items-start justify-center bg-black/40 px-3 pt-[12dvh] font-sans" onMouseDown={(e) => { if (e.target === e.currentTarget) onClose(); }}>
       <div role="dialog" aria-modal="true" aria-label="Search and go to" className="w-full max-w-xl overflow-hidden rounded-2xl border border-[var(--r-line)] bg-[var(--r-bar)] text-[var(--r-text)] shadow-2xl">
         <div className="flex items-center gap-2 border-b border-[var(--r-line)] px-4 py-3">
           <span className="text-[var(--r-sub)]"><SearchIcon /></span>
@@ -107,7 +107,7 @@ export default function CommandPalette({ onClose }) {
           />
           <kbd className="hidden rounded border border-[var(--r-line)] px-1.5 py-0.5 text-[10px] text-[var(--r-sub)] sm:block">esc</kbd>
         </div>
-        <ul id="palette-list" role="listbox" ref={listRef} className="max-h-[50vh] overflow-y-auto p-2">
+        <ul id="palette-list" role="listbox" ref={listRef} className="max-h-[50dvh] overflow-y-auto p-2">
           {items.length === 0 && <li className="px-3 py-6 text-center text-sm text-[var(--r-sub)]">Nothing found. Try a book and chapter, like “romans 8”.</li>}
           {items.map((item, i) => {
             const header = item.group !== lastGroup ? item.group : null;