📦 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/dependencies/URLPlugin.js

@@ -0,0 +1,67 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Ivan Kopeykin @vankop
+*/
+
+"use strict";
+
+const {
+	JAVASCRIPT_MODULE_TYPE_AUTO,
+	JAVASCRIPT_MODULE_TYPE_ESM
+} = require("../ModuleTypeConstants");
+
+const URLContextDependency = require("../dependencies/URLContextDependency");
+const URLDependency = require("../dependencies/URLDependency");
+const URLParserPlugin = require("../url/URLParserPlugin");
+
+/** @typedef {import("../../declarations/WebpackOptions").JavascriptParserOptions} JavascriptParserOptions */
+/** @typedef {import("../Compiler")} Compiler */
+/** @typedef {import("../javascript/JavascriptParser")} JavascriptParser */
+
+const PLUGIN_NAME = "URLPlugin";
+
+class URLPlugin {
+	/**
+	 * @param {Compiler} compiler compiler
+	 */
+	apply(compiler) {
+		compiler.hooks.compilation.tap(
+			PLUGIN_NAME,
+			(compilation, { normalModuleFactory, contextModuleFactory }) => {
+				compilation.dependencyFactories.set(URLDependency, normalModuleFactory);
+				compilation.dependencyTemplates.set(
+					URLDependency,
+					new URLDependency.Template()
+				);
+				compilation.dependencyFactories.set(
+					URLContextDependency,
+					contextModuleFactory
+				);
+				compilation.dependencyTemplates.set(
+					URLContextDependency,
+					new URLContextDependency.Template()
+				);
+
+				/**
+				 * @param {JavascriptParser} parser parser parser
+				 * @param {JavascriptParserOptions} parserOptions parserOptions
+				 * @returns {void}
+				 */
+				const handler = (parser, parserOptions) => {
+					if (parserOptions.url === false) return;
+					new URLParserPlugin(parserOptions).apply(parser);
+				};
+
+				normalModuleFactory.hooks.parser
+					.for(JAVASCRIPT_MODULE_TYPE_AUTO)
+					.tap(PLUGIN_NAME, handler);
+
+				normalModuleFactory.hooks.parser
+					.for(JAVASCRIPT_MODULE_TYPE_ESM)
+					.tap(PLUGIN_NAME, handler);
+			}
+		);
+	}
+}
+
+module.exports = URLPlugin;