📦 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/lodash/zip.js

@@ -0,0 +1,22 @@
+var baseRest = require('./_baseRest'),
+    unzip = require('./unzip');
+
+/**
+ * Creates an array of grouped elements, the first of which contains the
+ * first elements of the given arrays, the second of which contains the
+ * second elements of the given arrays, and so on.
+ *
+ * @static
+ * @memberOf _
+ * @since 0.1.0
+ * @category Array
+ * @param {...Array} [arrays] The arrays to process.
+ * @returns {Array} Returns the new array of grouped elements.
+ * @example
+ *
+ * _.zip(['a', 'b'], [1, 2], [true, false]);
+ * // => [['a', 1, true], ['b', 2, false]]
+ */
+var zip = baseRest(unzip);
+
+module.exports = zip;