📦 添加虚拟环境和启动脚本

新增:
- backend/venv/ - Python 虚拟环境
- backend/start.sh - 启动脚本（使用虚拟环境）
- backend/requirements.txt - 依赖列表
- .gitignore - 忽略虚拟环境和缓存文件

说明:
- 每个项目使用独立虚拟环境
- 避免依赖冲突
- 启动脚本自动创建和激活虚拟环境

frontend/node_modules/@babel/preset-modules/lib/plugins/transform-edge-default-parameters/index.js

@@ -0,0 +1,36 @@
+"use strict";
+
+exports.__esModule = true;
+exports.default = void 0;
+
+/**
+ * Converts destructured parameters with default values to non-shorthand syntax.
+ * This fixes the only arguments-related bug in ES Modules-supporting browsers (Edge 16 & 17).
+ * Use this plugin instead of @babel/plugin-transform-parameters when targeting ES Modules.
+ */
+var _default = ({
+  types: t
+}) => {
+  const isArrowParent = p => p.parentKey === "params" && p.parentPath && t.isArrowFunctionExpression(p.parentPath);
+
+  return {
+    name: "transform-edge-default-parameters",
+    visitor: {
+      AssignmentPattern(path) {
+        const arrowArgParent = path.find(isArrowParent);
+
+        if (arrowArgParent && path.parent.shorthand) {
+          // In Babel 7+, there is no way to force non-shorthand properties.
+          path.parent.shorthand = false;
+          (path.parent.extra || {}).shorthand = false; // So, to ensure non-shorthand, rename the local identifier so it no longer matches:
+
+          path.scope.rename(path.parent.key.name);
+        }
+      }
+
+    }
+  };
+};
+
+exports.default = _default;
+module.exports = exports.default;