feat: add Vue.js WebUI — YesPlayMusic-inspired SPA with all pages and components

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web/src/App.vue

@@ -0,0 +1,35 @@
+<template>
+  <div class="app" :data-theme="theme">
+    <Navbar />
+    <main class="main-content">
+      <RouterView />
+    </main>
+    <Player />
+  </div>
+</template>
+
+<script setup lang="ts">
+import { computed } from 'vue';
+import { usePlayerStore } from './stores/player.js';
+import Navbar from './components/Navbar.vue';
+import Player from './components/Player.vue';
+
+const playerStore = usePlayerStore();
+const theme = computed(() => playerStore.theme);
+</script>
+
+<style lang="scss">
+.app {
+  min-height: 100vh;
+  background: var(--bg-primary);
+  color: var(--text-primary);
+}
+
+.main-content {
+  padding: 80px 10vw 80px;
+
+  @media (max-width: 1336px) {
+    padding: 80px 5vw 80px;
+  }
+}
+</style>