📦 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/es-iterator-helpers/index.json

@@ -0,0 +1,21 @@
+[
+	"Iterator",
+	"Iterator.concat",
+	"Iterator.from",
+	"Iterator.zip",
+	"Iterator.zipKeyed",
+	"Iterator.prototype",
+	"Iterator.prototype.constructor",
+	"Iterator.prototype.drop",
+	"Iterator.prototype.every",
+	"Iterator.prototype.filter",
+	"Iterator.prototype.find",
+	"Iterator.prototype.flatMap",
+	"Iterator.prototype.forEach",
+	"Iterator.prototype.includes",
+	"Iterator.prototype.map",
+	"Iterator.prototype.reduce",
+	"Iterator.prototype.some",
+	"Iterator.prototype.take",
+	"Iterator.prototype.toArray"
+]