Refactor D-FINE module structure by removing obsolete detector file a…

…nd reorganizing imports

src/otx/algo/detection/d_fine.py

@@ -14,11 +14,11 @@
 from torchvision.ops import box_convert
 from torchvision.tv_tensors import BoundingBoxFormat
 
+from otx.algo.detection.backbones.hgnetv2 import HGNetv2
 from otx.algo.detection.detectors import DETR
-from otx.algo.detection.detectors.dfine.dfine_criterion import DFINECriterion
 from otx.algo.detection.detectors.dfine.dfine_decoder import DFINETransformer
-from otx.algo.detection.detectors.dfine.hgnetv2 import HGNetv2
-from otx.algo.detection.detectors.dfine.hybrid_encoder import HybridEncoder
+from otx.algo.detection.losses.dfine_loss import DFINECriterion
+from otx.algo.detection.necks.dfine_hybrid_encoder import HybridEncoder
 from otx.algo.utils.mmengine_utils import load_checkpoint
 from otx.core.config.data import TileConfig
 from otx.core.data.entity.base import OTXBatchLossEntity

src/otx/algo/detection/heads/__init__.py

@@ -3,10 +3,19 @@
 """Custom head implementations for detection task."""
 
 from .atss_head import ATSSHead
+from .dfine_decoder import DFINETransformer
 from .rtdetr_decoder import RTDETRTransformer
 from .rtmdet_head import RTMDetSepBNHead
 from .ssd_head import SSDHead
 from .yolo_head import YOLOHead
 from .yolox_head import YOLOXHead
 
-__all__ = ["ATSSHead", "RTDETRTransformer", "RTMDetSepBNHead", "SSDHead", "YOLOHead", "YOLOXHead"]
+__all__ = [
+    "ATSSHead",
+    "DFINETransformer",
+    "RTDETRTransformer",
+    "RTMDetSepBNHead",
+    "SSDHead",
+    "YOLOHead",
+    "YOLOXHead",
+]