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>

segmentation/deploy/configs/_base_/backends/tensorrt.py

@@ -0,0 +1,2 @@
+backend_config = dict(
+    type='tensorrt', common_config=dict(fp16_mode=False, max_workspace_size=0))