📦 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/fast-glob/out/utils/stream.js

@@ -0,0 +1,17 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.merge = void 0;
+const merge2 = require("merge2");
+function merge(streams) {
+    const mergedStream = merge2(streams);
+    streams.forEach((stream) => {
+        stream.once('error', (error) => mergedStream.emit('error', error));
+    });
+    mergedStream.once('close', () => propagateCloseEventToSources(streams));
+    mergedStream.once('end', () => propagateCloseEventToSources(streams));
+    return mergedStream;
+}
+exports.merge = merge;
+function propagateCloseEventToSources(streams) {
+    streams.forEach((stream) => stream.emit('close'));
+}