feat: 前端集成 Prettier 代码格式化

frontend/.vscode/extensions.json

@@ -0,0 +1,3 @@
+{
+  "recommendations": ["esbenp.prettier-vscode", "dbaeumer.vscode-eslint"]
+}

frontend/.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+  "editor.formatOnSave": true,
+  "editor.defaultFormatter": "esbenp.prettier-vscode",
+  "editor.codeActionsOnSave": {
+    "source.fixAll.eslint": "explicit"
+  }
+}