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>

package.json

@@ -5,7 +5,8 @@
   "type": "module",
   "scripts": {
     "dev": "tsx watch src/index.ts",
-    "build": "tsc",
+    "build": "tsc && npm run build:web",
+    "build:web": "cd web && npm run build",
     "start": "node dist/index.js",
     "test": "vitest run",
     "test:watch": "vitest"