Add image extraction functionality with background removal

- Implemented ExtractImageRegion operator for extracting image regions using box or lasso selection.
- Added RemoveImageRegionBackground job for background removal from selected image regions.
- Created utility functions for polygon bounds, selection canvas creation, and applying selection masks.
- Integrated image processing using PIL and numpy for efficient pixel manipulation.
- Enhanced user experience with modal drawing and status updates during extraction.

docs/index.md

@@ -9,6 +9,7 @@ AnyImage 是一款 Blender 扩展，可以把照片、视频或序列帧转换
 - 用 **Depth Plane** 快速得到可调节的浮雕式面片
 - 用 **Surface** 从单张图片生成透视纹理网格
 - 用 **Remove Background** 一键获得透明前景
+- 用 **Image Perspective** 将四点选区矫正为沿用源 Empty 朝向的矩形裁切图
 - 处理视频和序列帧，生成可随时间播放的 Depth Plane
 - 使用 Geometry Nodes 继续调整深度、细分、重拓扑与平滑效果