📦 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/eslint-plugin-import/docs/rules/no-dynamic-require.md

@@ -0,0 +1,25 @@
+# import/no-dynamic-require
+
+<!-- end auto-generated rule header -->
+
+The `require` method from CommonJS is used to import modules from different files. Unlike the ES6 `import` syntax, it can be given expressions that will be resolved at runtime. While this is sometimes necessary and useful, in most cases it isn't. Using expressions (for instance, concatenating a path and variable) as the argument makes it harder for tools to do static code analysis, or to find where in the codebase a module is used.
+
+This rule forbids every call to `require()` that uses expressions for the module name argument.
+
+## Rule Details
+
+### Fail
+
+```js
+require(name);
+require('../' + name);
+require(`../${name}`);
+require(name());
+```
+
+### Pass
+
+```js
+require('../name');
+require(`../name`);
+```