📦 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/differenceWith.js

@@ -0,0 +1,40 @@
+var baseDifference = require('./_baseDifference'),
+    baseFlatten = require('./_baseFlatten'),
+    baseRest = require('./_baseRest'),
+    isArrayLikeObject = require('./isArrayLikeObject'),
+    last = require('./last');
+
+/**
+ * This method is like `_.difference` except that it accepts `comparator`
+ * which is invoked to compare elements of `array` to `values`. The order and
+ * references of result values are determined by the first array. The comparator
+ * is invoked with two arguments: (arrVal, othVal).
+ *
+ * **Note:** Unlike `_.pullAllWith`, this method returns a new array.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category Array
+ * @param {Array} array The array to inspect.
+ * @param {...Array} [values] The values to exclude.
+ * @param {Function} [comparator] The comparator invoked per element.
+ * @returns {Array} Returns the new array of filtered values.
+ * @example
+ *
+ * var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
+ *
+ * _.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
+ * // => [{ 'x': 2, 'y': 1 }]
+ */
+var differenceWith = baseRest(function(array, values) {
+  var comparator = last(values);
+  if (isArrayLikeObject(comparator)) {
+    comparator = undefined;
+  }
+  return isArrayLikeObject(array)
+    ? baseDifference(array, baseFlatten(values, 1, isArrayLikeObject, true), undefined, comparator)
+    : [];
+});
+
+module.exports = differenceWith;