fix: OBB corner detection in convert_yolo_obb_to_annotation

[arda92a]

Fix OBB Corner Detection in convert_yolo_obb_to_annotation

Problem

The previous implementation calculated the top-left corner of oriented bounding boxes (OBBs) using geometric transformations from the center point. This approach could produce incorrect corner positions, especially for rotated boxes, as it relied on assumptions about coordinate ordering that may not hold for all YOLO OBB outputs.

Solution

This PR refactors the corner detection logic to explicitly identify the actual top-left corner from the provided coordinates:

1. Sort by X-coordinate to separate left-side points from right-side points
2. Identify top-left corner as the left-most point with the smallest Y-coordinate
3. Identify bottom-left corner as the left-most point with the largest Y-coordinate
4. Identify top-right corner as the right-most point with the smallest Y-coordinate
5. Calculate dimensions directly from corner-to-corner distances (TL→TR for width, TL→BL for height)

Changes

• Replaced center-based calculation with explicit corner detection
• Width is now calculated as the distance between top-left and top-right corners
• Height is now calculated as the distance between top-left and bottom-left corners
• Rotation angle calculation remains unchanged (angle between top-left and top-right)