feat(frontend): 搭建桌面端基础界面与 Workspace

- App Shell 壳层：主导航、次导航、Title Bar、状态栏
- Vault 入口页：最近 Vault、打开/创建 Vault、AI Core 状态
- Workspace 与文件树：浏览、打开、创建笔记/文件夹
- Design Token：浅色/深色主题 CSS Variables
- Contracts / Service / Store / Router 基础架构
- 统一 ApiClient 与 SseClient，对接后端 API 契约

frontend/package.json

@@ -6,16 +6,33 @@
   "scripts": {
     "dev": "vite",
     "build": "vue-tsc -b && vite build",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "type-check": "vue-tsc --noEmit"
   },
   "dependencies": {
-    "vue": "latest"
+    "@codemirror/lang-markdown": "^6.5.0",
+    "@codemirror/theme-one-dark": "^6.1.0",
+    "@milkdown/plugin-block": "^7.22.0",
+    "@milkdown/plugin-cursor": "^7.22.0",
+    "@milkdown/plugin-history": "^7.22.0",
+    "@milkdown/plugin-listener": "^7.22.0",
+    "@milkdown/plugin-slash": "^7.22.0",
+    "@milkdown/plugin-tooltip": "^7.22.0",
+    "@milkdown/plugin-trailing": "^7.22.0",
+    "@milkdown/theme-nord": "^7.22.0",
+    "@milkdown/vue": "^7.22.0",
+    "@vueuse/core": "^14.0.0",
+    "codemirror": "^6.0.0",
+    "marked": "^15.0.0",
+    "pinia": "^4.0.0",
+    "vue": "^3.5.0",
+    "vue-router": "^5.0.0"
   },
   "devDependencies": {
-    "@types/node": "latest",
-    "@vitejs/plugin-vue": "latest",
+    "@types/node": "^22.0.0",
+    "@vitejs/plugin-vue": "^5.0.0",
     "typescript": "~5.9.3",
-    "vite": "latest",
-    "vue-tsc": "latest"
+    "vite": "^6.0.0",
+    "vue-tsc": "^2.0.0"
   }
 }