📦 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/@webassemblyjs/helper-wasm-section/lib/index.js

@@ -0,0 +1,35 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+Object.defineProperty(exports, "resizeSectionByteSize", {
+  enumerable: true,
+  get: function get() {
+    return _resize.resizeSectionByteSize;
+  }
+});
+Object.defineProperty(exports, "resizeSectionVecSize", {
+  enumerable: true,
+  get: function get() {
+    return _resize.resizeSectionVecSize;
+  }
+});
+Object.defineProperty(exports, "createEmptySection", {
+  enumerable: true,
+  get: function get() {
+    return _create.createEmptySection;
+  }
+});
+Object.defineProperty(exports, "removeSections", {
+  enumerable: true,
+  get: function get() {
+    return _remove.removeSections;
+  }
+});
+
+var _resize = require("./resize");
+
+var _create = require("./create");
+
+var _remove = require("./remove");