📦 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/_baseConformsTo.js

@@ -0,0 +1,27 @@
+/**
+ * The base implementation of `_.conformsTo` which accepts `props` to check.
+ *
+ * @private
+ * @param {Object} object The object to inspect.
+ * @param {Object} source The object of property predicates to conform to.
+ * @returns {boolean} Returns `true` if `object` conforms, else `false`.
+ */
+function baseConformsTo(object, source, props) {
+  var length = props.length;
+  if (object == null) {
+    return !length;
+  }
+  object = Object(object);
+  while (length--) {
+    var key = props[length],
+        predicate = source[key],
+        value = object[key];
+
+    if ((value === undefined && !(key in object)) || !predicate(value)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+module.exports = baseConformsTo;