📦 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/schemas/plugins/debug/ProfilingPlugin.check.d.ts

@@ -0,0 +1,7 @@
+/*
+ * This file was automatically generated.
+ * DO NOT MODIFY BY HAND.
+ * Run `yarn fix:special` to update
+ */
+declare const check: (options: import("../../../declarations/plugins/debug/ProfilingPlugin").ProfilingPluginOptions) => boolean;
+export = check;

frontend/node_modules/webpack/schemas/plugins/debug/ProfilingPlugin.check.js

@@ -0,0 +1,6 @@
+/*
+ * This file was automatically generated.
+ * DO NOT MODIFY BY HAND.
+ * Run `yarn fix:special` to update
+ */
+const r=/^(?:[A-Za-z]:[\\/]|\\\\|\/)/;function t(e,{instancePath:a="",parentData:o,parentDataProperty:n,rootData:s=e}={}){if(!e||"object"!=typeof e||Array.isArray(e))return t.errors=[{params:{type:"object"}}],!1;{const a=0;for(const r in e)if("outputPath"!==r)return t.errors=[{params:{additionalProperty:r}}],!1;if(0===a&&void 0!==e.outputPath){let a=e.outputPath;if("string"!=typeof a)return t.errors=[{params:{type:"string"}}],!1;if(a.includes("!")||!0!==r.test(a))return t.errors=[{params:{}}],!1}}return t.errors=null,!0}module.exports=t,module.exports.default=t;

frontend/node_modules/webpack/schemas/plugins/debug/ProfilingPlugin.json

@@ -0,0 +1,12 @@
+{
+  "title": "ProfilingPluginOptions",
+  "type": "object",
+  "additionalProperties": false,
+  "properties": {
+    "outputPath": {
+      "description": "Path to the output file e.g. `path.resolve(__dirname, 'profiling/events.json')`. Defaults to `events.json`.",
+      "type": "string",
+      "absolutePath": true
+    }
+  }
+}