📦 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/static-eval/CHANGELOG.md

@@ -0,0 +1,21 @@
+# static-eval Change Log
+All notable changes to this project will be documented in this file.
+This project adheres to [Semantic Versioning](http://semver.org/).
+
+## 2.1.1
+* Update `escodegen`. [@FabianWarnecke](https://github.com/FabianWarnecke) in [#43](https://github.com/browserify/static-eval/pull/43)
+
+  escodegen doesn't officially support all the Node.js versions that `static-eval` supports, but so far it still works on them.
+  This has been the case for both v1.x and v2.1.0 of escodegen, so the upgrade doesn't change that situation.
+
+## 2.1.0
+* Add `allowAccessToMethodsOnFunctions` option to restore 1.x behaviour so that [cwise](https://github.com/scijs/cwise) can upgrade. ([@archmoj](https://github.com/archmoj) in [#31](https://github.com/browserify/static-eval/pull/31))
+
+  Do not use this option if you are not sure that you need it, as it had previously been removed for security reasons. There is a known exploit to execute arbitrary code. Only use it on trusted inputs, like the developer's JS files in a build system.
+
+## 2.0.5
+* Fix function bodies being invoked during declaration. ([@RoboPhred](https://github.com/RoboPhred) in [#30](https://github.com/browserify/static-eval/pull/30))
+
+## 2.0.4
+* Short-circuit evaluation in `&&` and `||` expressions. ([@RoboPhred](https://github.com/RoboPhred) in [#28](https://github.com/browserify/static-eval/pull/28))
+* Start tracking changes.