refactor: 重命名SDK为iflow-engine，使用npm包引入第三方引擎

- 将包名从 @fishdingding/bim-engine-sdk 改为 iflow-engine
- 将构建输出文件从 bim-engine-sdk.*.js 改为 iflow-engine.*.js
- 将全局变量从 LyzBimEngineSDK 改为 IflowEngine
- 将第三方引擎SDK从本地引入改为npm包引入 (iflow-engine-base)
- 移除本地 src/engine_base 目录，移至回收站
- 更新所有文档和demo中的引用

demo-vue/src/App.vue

@@ -2,7 +2,7 @@
   <div class="app-container">
     <!-- 左侧控制面板 -->
     <aside class="sidebar">
-      <h1>BIM SDK Demo (Vue3)</h1>
+      <h1>iFlow Engine Demo (Vue3)</h1>
 
       <!-- 1. 语言设置 -->
       <div class="control-group">
@@ -84,8 +84,8 @@ const engineStatusColor = ref('#666');
 
 // 初始化引擎
 onMounted(() => {
-  if (window.LyzBimEngineSDK) {
-    const Engine = window.LyzBimEngineSDK.BimEngine;
+  if (window.IflowEngine) {
+    const Engine = window.IflowEngine.BimEngine;
     try {
       if (appContainer.value) {
         engine.value = new Engine(appContainer.value, { locale: 'zh-CN' });

demo-vue/src/vite-env.d.ts

@@ -9,7 +9,7 @@ declare module '*.vue' {
 // 声明全局 SDK 类型
 declare global {
   interface Window {
-    LyzBimEngineSDK: {
+    IflowEngine: {
       BimEngine: any;
     };
   }