📦 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/eslint/lib/cli-engine/load-rules.js

@@ -0,0 +1,46 @@
+/**
+ * @fileoverview Module for loading rules from files and directories.
+ * @author Michael Ficarra
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const fs = require("fs"),
+    path = require("path");
+
+const rulesDirCache = {};
+
+//------------------------------------------------------------------------------
+// Public Interface
+//------------------------------------------------------------------------------
+
+/**
+ * Load all rule modules from specified directory.
+ * @param {string} relativeRulesDir Path to rules directory, may be relative.
+ * @param {string} cwd Current working directory
+ * @returns {Object} Loaded rule modules.
+ */
+module.exports = function(relativeRulesDir, cwd) {
+    const rulesDir = path.resolve(cwd, relativeRulesDir);
+
+    // cache will help performance as IO operation are expensive
+    if (rulesDirCache[rulesDir]) {
+        return rulesDirCache[rulesDir];
+    }
+
+    const rules = Object.create(null);
+
+    fs.readdirSync(rulesDir).forEach(file => {
+        if (path.extname(file) !== ".js") {
+            return;
+        }
+        rules[file.slice(0, -3)] = require(path.join(rulesDir, file));
+    });
+    rulesDirCache[rulesDir] = rules;
+
+    return rules;
+};