chore: 将前端移动到 client/ 目录，准备合并为单仓库

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

client/package.json

@@ -0,0 +1,42 @@
+{
+  "name": "web",
+  "private": true,
+  "version": "0.3.0",
+  "type": "module",
+  "scripts": {
+    "start": "rsbuild dev",
+    "build": "rsbuild build",
+    "build:staging": "rsbuild build --env-mode staging",
+    "fmt": "prettier --write src/"
+  },
+  "dependencies": {
+    "@codemirror/lang-css": "^6.3.1",
+    "@codemirror/lang-html": "^6.4.12",
+    "@codemirror/lang-javascript": "^6.2.5",
+    "@vueuse/core": "^14.4.0",
+    "axios": "^1.19.0",
+    "codemirror": "^6.0.2",
+    "copy-text-to-clipboard": "^3.2.2",
+    "github-markdown-css": "^5.9.0",
+    "highlight.js": "^11.12.0",
+    "marked": "^18.0.9",
+    "marked-alert": "^2.1.2",
+    "marked-code-preview": "^1.3.7",
+    "marked-highlight": "^2.2.4",
+    "md-editor-v3": "^6.5.6",
+    "naive-ui": "^2.44.1",
+    "vue": "^3.5.41",
+    "vue-codemirror": "^6.1.1",
+    "vue-router": "^5.2.0"
+  },
+  "devDependencies": {
+    "@iconify/vue": "^5.0.1",
+    "@rsbuild/core": "^2.1.13",
+    "@rsbuild/plugin-vue": "^2.0.1",
+    "@vue/tsconfig": "^0.9.1",
+    "core-js": "^3.50.0",
+    "prettier": "^3.9.6",
+    "typescript": "^7.0.2",
+    "unplugin-vue-components": "^32.1.0"
+  }
+}