Redesign UI with zen cards, split AI panel, and PWA install support.

Learn uses 64-gua card grid; liuyao/bazi/combined use two input cards plus sticky right AI panel; add manifest, service worker, and install prompt.

Co-authored-by: Cursor <cursoragent@cursor.com>

components/header.tsx

@@ -34,8 +34,8 @@ function NavLink({ href, label }: { href: string; label: string }) {
 
 export default function Header() {
   return (
-    <header className="bg-secondary py-2 shadow">
-      <div className="mx-auto flex w-full max-w-4xl flex-col gap-2 px-4 sm:flex-row sm:items-center sm:justify-between">
+    <header className="border-b border-border/40 bg-card/60 py-3 shadow-sm backdrop-blur-md">
+      <div className="mx-auto flex w-full max-w-6xl flex-col gap-2 px-4 sm:flex-row sm:items-center sm:justify-between">
         <Link href="/" className="flex items-center justify-center gap-2 sm:justify-start">
           <ChatGPT />
           <span className="font-medium">知命阁</span>