Migrate to Vite + ES module architecture

Split monolithic app.js (~1850 lines) into maintainable ES modules:
- src/state.js  — shared mutable state (S object)
- src/utils.js  — md5, esc, formatDur, toast
- src/api.js    — Subsonic API, Navidrome REST, iTunes API
- src/player.js — playback, transport, queue, media session, preview
- src/views.js  — navigation, page loaders, card makers, search
- src/ui.js     — all modals, overlays, sidebar, settings
- src/pwa.js    — service worker registration + update banner
- src/main.js   — app init, connect, window globals

Updated Dockerfile to multi-stage (Node build → nginx serve).
Static assets (sw.js, manifest.json, icon.svg) moved to public/.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/config.js

@@ -0,0 +1 @@
+

public/icon.svg

@@ -0,0 +1,22 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512">
+  <rect width="512" height="512" rx="90" fill="#07070f"/>
+  <rect width="512" height="512" rx="90" fill="url(#bg)"/>
+  <defs>
+    <radialGradient id="bg" cx="30%" cy="40%" r="80%">
+      <stop offset="0%" stop-color="#1a1a2e"/>
+      <stop offset="100%" stop-color="#07070f"/>
+    </radialGradient>
+  </defs>
+  <!-- Music note -->
+  <g fill="#e8a020">
+    <!-- Note head 1 -->
+    <ellipse cx="180" cy="340" rx="48" ry="36" transform="rotate(-15 180 340)"/>
+    <!-- Note head 2 -->
+    <ellipse cx="332" cy="300" rx="48" ry="36" transform="rotate(-15 332 300)"/>
+    <!-- Stem -->
+    <rect x="218" y="160" width="18" height="185" rx="9"/>
+    <rect x="370" y="120" width="18" height="185" rx="9"/>
+    <!-- Beam -->
+    <rect x="218" y="160" width="170" height="22" rx="11"/>
+  </g>
+</svg>

public/manifest.json

@@ -0,0 +1,25 @@
+{
+  "name": "NovaSonic",
+  "short_name": "NovaSonic",
+  "description": "Self-hosted music streaming PWA",
+  "start_url": "/",
+  "scope": "/",
+  "display": "standalone",
+  "orientation": "portrait-primary",
+  "background_color": "#07070f",
+  "theme_color": "#07070f",
+  "icons": [
+    {
+      "src": "icon.svg",
+      "sizes": "any",
+      "type": "image/svg+xml",
+      "purpose": "any"
+    },
+    {
+      "src": "icon.svg",
+      "sizes": "any",
+      "type": "image/svg+xml",
+      "purpose": "maskable"
+    }
+  ]
+}

public/sw.js

@@ -0,0 +1,40 @@
+const CACHE = 'ns-v38';
+const PRECACHE = ['/', 'index.html', 'manifest.json', 'icon.svg'];
+const SKIP_PATHS = ['/rest/stream', '/rest/download', '/config.js'];
+
+self.addEventListener('install', e => {
+  e.waitUntil(caches.open(CACHE).then(c => c.addAll(PRECACHE)));
+  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())
+      .then(() => self.clients.matchAll({ type: 'window', includeUncontrolled: true }))
+      .then(clients => clients.forEach(c => c.postMessage({ type: 'SW_UPDATED', version: CACHE })))
+  );
+});
+
+self.addEventListener('message', e => {
+  if (e.data?.type === 'GET_VERSION') {
+    e.source.postMessage({ type: 'VERSION', version: CACHE });
+  }
+});
+
+self.addEventListener('fetch', e => {
+  if (!e.request.url.startsWith(self.location.origin)) return;
+  if (SKIP_PATHS.some(p => e.request.url.includes(p))) return;
+  e.respondWith(
+    fetch(e.request)
+      .then(res => {
+        if (res.status === 200 && e.request.method === 'GET') {
+          const clone = res.clone();
+          caches.open(CACHE).then(c => c.put(e.request, clone));
+        }
+        return res;
+      })
+      .catch(() => caches.match(e.request).then(r => r || Response.error()))
+  );
+});