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

.recycle/2026-01-22/src/assets/bim-engine-sdk.GWPzrvC_.css

@@ -0,0 +1 @@
+.ViewCube{position:absolute;width:120px;height:120px;top:0;right:0;z-index:999}.homeViewWrapper{position:absolute;cursor:pointer;pointer-events:auto;background-image:url(assets/viewcube/home.png);background-size:100% 100%;background-repeat:no-repeat;background-color:#fff;color:#fff;top:10px;right:100;width:20px;height:20px;z-index:999}.measure-elevation{position:absolute;pointer-events:none}.measureSvg{position:absolute;width:1920px;height:1080px}.catch-point{position:absolute;width:10px;height:10px;background-color:red;border-radius:50%;pointer-events:none}.annotation-container{position:absolute;pointer-events:none;top:0;left:0}.measureLine{position:absolute;pointer-events:none}.measureBack{cursor:pointer;pointer-events:auto;fill:orange;top:-50px;rx:5;ry:5}.measureLabel{position:absolute;fill:#fff;font-size:14px;font-family:Arial,sans-serif}.measurePointer{fill:orange}.Hight{stroke:#fff;stroke-width:2}.allow-select{pointer-events:auto}.disallow-select{pointer-events:none}.angle-annotation{position:absolute;pointer-events:auto}