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>

public/sw.js

@@ -0,0 +1,11 @@
+self.addEventListener("install", (event) => {
+  event.waitUntil(self.skipWaiting());
+});
+
+self.addEventListener("activate", (event) => {
+  event.waitUntil(self.clients.claim());
+});
+
+self.addEventListener("fetch", (event) => {
+  event.respondWith(fetch(event.request));
+});