feat: theme system with persistent selection and Dark Ocean starter theme

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

src/main.js

@@ -2,6 +2,7 @@ import { S } from './state.js';
 import { toast } from './utils.js';
 import { api } from './api.js';
 import { injectPWA } from './pwa.js';
+import { loadSavedTheme } from './themes.js';
 import {
   playQueue, playCurrent, togglePlay, prevSong, nextSong, onEnded,
   toggleShuffle, toggleRepeat, toggleQueue, setVolume, seekTo,
@@ -31,6 +32,7 @@ import {
   deletePlaylist, _confirmOk, _confirmCancel,
   toggleMobileSearch, closeMobileSearch, switchSetupTab,
   toggleNotifPanel, deleteNotif, clearNotifs, initNotifBell, _notifNavigate,
+  _pickTheme,
 } from './ui.js';
 
 // ─── CONNECT ───
@@ -92,6 +94,8 @@ async function startApp() {
 
 // ─── INIT ───
 window.addEventListener('load', () => {
+  loadSavedTheme();
+
   // Wire up audio elements from DOM
   S.audio        = document.getElementById('audio-element');
   S.previewAudio = document.getElementById('preview-audio');
@@ -241,7 +245,7 @@ Object.assign(window, {
   openEditPlModal, closeEditPlModal, saveEditPlaylist,
   editPlUploadCover, editPlCoverSelected, editPlRemoveCover, deletePlaylist, _confirmOk, _confirmCancel,
   toggleMobileSearch, closeMobileSearch, switchSetupTab,
-  toggleNotifPanel, deleteNotif, clearNotifs, _notifNavigate,
+  toggleNotifPanel, deleteNotif, clearNotifs, _notifNavigate, _pickTheme,
   // App
   doConnect, disconnect,
 });