add app, fix ble, use flash

app/sw.js

@@ -0,0 +1,31 @@
+// sw.js — minimal offline cache so the PWA launches without a network.
+const CACHE = 'babymobile-v2';
+const ASSETS = [
+  './', './index.html', './styles.css',
+  './app.js', './ble.js', './wav.js',
+  './manifest.webmanifest', './icon.svg',
+];
+
+self.addEventListener('install', (e) => {
+  e.waitUntil(caches.open(CACHE).then((c) => c.addAll(ASSETS)).then(() => self.skipWaiting()));
+});
+
+self.addEventListener('activate', (e) => {
+  e.waitUntil(
+    caches.keys().then((keys) => Promise.all(keys.filter((k) => k !== CACHE).map((k) => caches.delete(k))))
+      .then(() => self.clients.claim())
+  );
+});
+
+// Cache-first for app shell; network passthrough otherwise.
+self.addEventListener('fetch', (e) => {
+  const url = new URL(e.request.url);
+  if (e.request.method !== 'GET' || url.origin !== location.origin) return;
+  e.respondWith(
+    caches.match(e.request).then((hit) => hit || fetch(e.request).then((res) => {
+      const copy = res.clone();
+      caches.open(CACHE).then((c) => c.put(e.request, copy)).catch(() => {});
+      return res;
+    }).catch(() => hit))
+  );
+});