Initial commit: DCNv4 custom op mirror setup

- Add enhanced README with project structure and quick start guide
- Initialize repository with DCNv4 CUDA extension (PyTorch module)
- Include classification, detection, and segmentation subdirectories
- Reference upstream OpenGVLab DCNv4 implementation

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

detection/tools/evaluate/__init__.py

@@ -0,0 +1,2 @@
+from .compute_APMR import compute_APMR
+from .compute_JI import compute_JI_with_ignore