📦 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/prefetch/ChunkPrefetchStartupRuntimeModule.js

@@ -0,0 +1,56 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+*/
+
+"use strict";
+
+const RuntimeGlobals = require("../RuntimeGlobals");
+const RuntimeModule = require("../RuntimeModule");
+const Template = require("../Template");
+
+/** @typedef {import("../Chunk")} Chunk */
+/** @typedef {import("../Chunk").ChunkChildOfTypeInOrder} ChunkChildOfTypeInOrder */
+/** @typedef {import("../Compilation")} Compilation */
+
+class ChunkPrefetchStartupRuntimeModule extends RuntimeModule {
+	/**
+	 * @param {ChunkChildOfTypeInOrder[]} startupChunks chunk ids to trigger when chunks are loaded
+	 */
+	constructor(startupChunks) {
+		super("startup prefetch", RuntimeModule.STAGE_TRIGGER);
+		/** @type {ChunkChildOfTypeInOrder[]} */
+		this.startupChunks = startupChunks;
+	}
+
+	/**
+	 * @returns {string | null} runtime code
+	 */
+	generate() {
+		const { startupChunks } = this;
+		const compilation = /** @type {Compilation} */ (this.compilation);
+		const chunk = /** @type {Chunk} */ (this.chunk);
+		const { runtimeTemplate } = compilation;
+		return Template.asString(
+			startupChunks.map(
+				({ onChunks, chunks }) =>
+					`${RuntimeGlobals.onChunksLoaded}(0, ${JSON.stringify(
+						// This need to include itself to delay execution after this chunk has been fully loaded
+						onChunks.filter((c) => c === chunk).map((c) => c.id)
+					)}, ${runtimeTemplate.basicFunction(
+						"",
+						chunks.size < 3
+							? Array.from(
+									chunks,
+									(c) =>
+										`${RuntimeGlobals.prefetchChunk}(${JSON.stringify(c.id)});`
+								)
+							: `${JSON.stringify(Array.from(chunks, (c) => c.id))}.map(${
+									RuntimeGlobals.prefetchChunk
+								});`
+					)}, 5);`
+			)
+		);
+	}
+}
+
+module.exports = ChunkPrefetchStartupRuntimeModule;