📦 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/fs-monkey/lib/correctPath.js

@@ -0,0 +1,43 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.correctPath = correctPath;
+exports.unixify = unixify;
+var isWin = process.platform === 'win32';
+function removeTrailingSeparator(str) {
+  var i = str.length - 1;
+  if (i < 2) {
+    return str;
+  }
+  while (isSeparator(str, i)) {
+    i--;
+  }
+  return str.substr(0, i + 1);
+}
+function isSeparator(str, i) {
+  var _char = str[i];
+  return i > 0 && (_char === '/' || isWin && _char === '\\');
+}
+function normalizePath(str, stripTrailing) {
+  if (typeof str !== 'string') {
+    throw new TypeError('expected a string');
+  }
+  str = str.replace(/[\\\/]+/g, '/');
+  if (stripTrailing !== false) {
+    str = removeTrailingSeparator(str);
+  }
+  return str;
+}
+function unixify(filepath) {
+  var stripTrailing = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : true;
+  if (isWin) {
+    filepath = normalizePath(filepath, stripTrailing);
+    return filepath.replace(/^([a-zA-Z]+:|\.\/)/, '');
+  }
+  return filepath;
+}
+function correctPath(filepath) {
+  return unixify(filepath.replace(/^\\\\\?\\.:\\/, '\\'));
+}