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>

.gitignore

@@ -0,0 +1,28 @@
+
+.idea/
+.DS_Store
+__pycache__/
+classification/convertor/
+segmentation/convertor/
+checkpoint_dir/
+demo/
+detection/work_dirs
+*.pth
+ops_dcnv3/build
+ops_dcnv3/dist
+ops_dcnv3/DCNv3.egg-info
+DCNv4_op/DCNv4.egg-info
+build/
+dist/
+ckpts/
+ckpts
+data
+data/
+detection/data
+detection/ckpts
+segmentation/data
+segmentation/ckpts
+work_dirs/
+output
+*.so
+DCNv4_op/DCNv4/*.so