📦 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/json/JsonData.js

@@ -0,0 +1,74 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const { register } = require("../util/serialization");
+
+/** @typedef {import("../serialization/ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
+/** @typedef {import("../serialization/ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */
+/** @typedef {import("../util/Hash")} Hash */
+/** @typedef {import("../util/fs").JsonValue} JsonValue */
+
+class JsonData {
+	/**
+	 * @param {Buffer | JsonValue} data JSON data
+	 */
+	constructor(data) {
+		/** @type {Buffer | undefined} */
+		this._buffer = undefined;
+		/** @type {JsonValue | undefined} */
+		this._data = undefined;
+		if (Buffer.isBuffer(data)) {
+			this._buffer = data;
+		} else {
+			this._data = data;
+		}
+	}
+
+	/**
+	 * @returns {JsonValue | undefined} Raw JSON data
+	 */
+	get() {
+		if (this._data === undefined && this._buffer !== undefined) {
+			this._data = JSON.parse(this._buffer.toString());
+		}
+		return this._data;
+	}
+
+	/**
+	 * @param {Hash} hash hash to be updated
+	 * @returns {void} the updated hash
+	 */
+	updateHash(hash) {
+		if (this._buffer === undefined && this._data !== undefined) {
+			this._buffer = Buffer.from(JSON.stringify(this._data));
+		}
+
+		if (this._buffer) hash.update(this._buffer);
+	}
+}
+
+register(JsonData, "webpack/lib/json/JsonData", null, {
+	/**
+	 * @param {JsonData} obj JSONData object
+	 * @param {ObjectSerializerContext} context context
+	 */
+	serialize(obj, { write }) {
+		if (obj._buffer === undefined && obj._data !== undefined) {
+			obj._buffer = Buffer.from(JSON.stringify(obj._data));
+		}
+		write(obj._buffer);
+	},
+	/**
+	 * @param {ObjectDeserializerContext} context context
+	 * @returns {JsonData} deserialized JSON data
+	 */
+	deserialize({ read }) {
+		return new JsonData(read());
+	}
+});
+
+module.exports = JsonData;