📦 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/webpack/lib/InvalidDependenciesModuleWarning.js

@@ -0,0 +1,44 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const WebpackError = require("./WebpackError");
+const makeSerializable = require("./util/makeSerializable");
+
+/** @typedef {import("./Module")} Module */
+
+class InvalidDependenciesModuleWarning extends WebpackError {
+	/**
+	 * @param {Module} module module tied to dependency
+	 * @param {Iterable<string>} deps invalid dependencies
+	 */
+	constructor(module, deps) {
+		const orderedDeps = deps ? [...deps].sort() : [];
+		const depsList = orderedDeps.map((dep) => ` * ${JSON.stringify(dep)}`);
+		super(`Invalid dependencies have been reported by plugins or loaders for this module. All reported dependencies need to be absolute paths.
+Invalid dependencies may lead to broken watching and caching.
+As best effort we try to convert all invalid values to absolute paths and converting globs into context dependencies, but this is deprecated behavior.
+Loaders: Pass absolute paths to this.addDependency (existing files), this.addMissingDependency (not existing files), and this.addContextDependency (directories).
+Plugins: Pass absolute paths to fileDependencies (existing files), missingDependencies (not existing files), and contextDependencies (directories).
+Globs: They are not supported. Pass absolute path to the directory as context dependencies.
+The following invalid values have been reported:
+${depsList.slice(0, 3).join("\n")}${
+			depsList.length > 3 ? "\n * and more ..." : ""
+		}`);
+
+		/** @type {string} */
+		this.name = "InvalidDependenciesModuleWarning";
+		this.details = depsList.slice(3).join("\n");
+		this.module = module;
+	}
+}
+
+makeSerializable(
+	InvalidDependenciesModuleWarning,
+	"webpack/lib/InvalidDependenciesModuleWarning"
+);
+
+module.exports = InvalidDependenciesModuleWarning;