feat: upgrade iflow-engine-base to v1.0.5, add pause/resume rendering API

- Update iflow-engine-base from 1.0.1 to 1.0.5
- Change default engine version from v1 to v2
- Add pauseRendering() and resumeRendering() methods
- Add switch model feature in demos
- Update model URLs in demos
- Add new documentation files

demo/viewer.html

@@ -127,7 +127,7 @@
 
             try {
                 // 加载模型文件（从 model 目录）- 使用与 index.html 相同的模型路径
-                const modelUrl = './model/test2';
+                const modelUrl = 'https://lyz-1259524260.cos.ap-guangzhou.myqcloud.com/iflow/models/8634e556-a94e-4ba7-be3e-2ea1507cced5/';
 
                 engine.engine.loadModel(modelUrl, {
                     position: [0, 0, 0],    // 初始位置