抽屉菜单打磨：面板收窄到 min(66vw,250px)，字重 800→500 配 Phosphor 图标，当前项改淡色胶囊高亮（引入 @phosphor-icons/vue 按需引入）

frontend/package.json

@@ -16,6 +16,7 @@
     "@codemirror/state": "^6.7.6",
     "@codemirror/view": "^6.43.13",
     "@milkdown/crepe": "^7.22.1",
+    "@phosphor-icons/vue": "^2.2.1",
     "dompurify": "^3.1.6",
     "vue": "^3.4.0",
     "vue-router": "^4.4.0"