📦 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/util/ArrayQueue.js

@@ -0,0 +1,104 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+/**
+ * @template T
+ */
+class ArrayQueue {
+	/**
+	 * @param {Iterable<T>=} items The initial elements.
+	 */
+	constructor(items) {
+		/**
+		 * @private
+		 * @type {T[]}
+		 */
+		this._list = items ? [...items] : [];
+		/**
+		 * @private
+		 * @type {T[]}
+		 */
+		this._listReversed = [];
+	}
+
+	/**
+	 * Returns the number of elements in this queue.
+	 * @returns {number} The number of elements in this queue.
+	 */
+	get length() {
+		return this._list.length + this._listReversed.length;
+	}
+
+	/**
+	 * Empties the queue.
+	 */
+	clear() {
+		this._list.length = 0;
+		this._listReversed.length = 0;
+	}
+
+	/**
+	 * Appends the specified element to this queue.
+	 * @param {T} item The element to add.
+	 * @returns {void}
+	 */
+	enqueue(item) {
+		this._list.push(item);
+	}
+
+	/**
+	 * Retrieves and removes the head of this queue.
+	 * @returns {T | undefined} The head of the queue of `undefined` if this queue is empty.
+	 */
+	dequeue() {
+		if (this._listReversed.length === 0) {
+			if (this._list.length === 0) return;
+			if (this._list.length === 1) return this._list.pop();
+			if (this._list.length < 16) return this._list.shift();
+			const temp = this._listReversed;
+			this._listReversed = this._list;
+			this._listReversed.reverse();
+			this._list = temp;
+		}
+		return this._listReversed.pop();
+	}
+
+	/**
+	 * Finds and removes an item
+	 * @param {T} item the item
+	 * @returns {void}
+	 */
+	delete(item) {
+		const i = this._list.indexOf(item);
+		if (i >= 0) {
+			this._list.splice(i, 1);
+		} else {
+			const i = this._listReversed.indexOf(item);
+			if (i >= 0) this._listReversed.splice(i, 1);
+		}
+	}
+
+	[Symbol.iterator]() {
+		return {
+			next: () => {
+				const item = this.dequeue();
+				if (item) {
+					return {
+						done: false,
+						value: item
+					};
+				}
+				return {
+					done: true,
+					value: undefined
+				};
+			}
+		};
+	}
+}
+
+module.exports = ArrayQueue;