fix(yolo): round polygon coords before int cast to improve mask accuracy

[Pranay0302]

Before submitting

• Self-reviewed the code
• Updated documentation (if applicable), following Google-style
• Added docs entry for autogeneration (if new functions/classes)
• Added/updated tests
• All tests pass locally

Description

Improve YOLO polygon-to-mask conversion accuracy by rounding scaled polygon coordinates before integer casting. This removes a consistent top-left bias introduced by flooring behavior when coordinates contain decimals greater than 0.5.

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• 🧪 Test update

Motivation and Context

YOLO polygon annotations are stored as relative (float) coordinates. During mask conversion, coordinates were implicitly floored when cast to int, shifting polygons toward the top-left and producing inaccurate masks. This PR basically switches to rounding before integer conversion to align pixels correctly.

Closes #2023

Changes Made

• Updated YOLO polygon scaling logic to apply np.round() prior to astype(int) to avoid systematic flooring bias.
• Ensured scaling uses resolution_wh as float32 to prevent premature integer casting.
• Added a regression test covering decimal polygon coordinates greater than 0.5 to validate rounding behavior.

Testing

• I have tested this code locally
• I have added unit tests that prove my fix is effective or that my feature works
• All new and existing tests pass

Notes:

• 22 YOLO format tests pass
• 112 total dataset tests pass

Additional Notes

This is a non-breaking change that only affects polygon-to-mask conversion accuracy for YOLO polygon annotations with fractional coordinates.

[CLAassistant]

All committers have signed the CLA.

[Pranay0302]

Hey @SkalskiP, would you be able to review this?

[Pranay0302]

Hey @Borda , when you have a moment could you please take a look at this PR and let me know if everything looks good on your end? Appreciate the review!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 52%. Comparing base (8419279) to head (777b183).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #2080   +/-   ##
=======================================
  Coverage       52%     52%           
=======================================
  Files           61      61           
  Lines         7076    7076           
=======================================
  Hits          3657    3657           
  Misses        3419    3419           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[SkalskiP]

Hi @Pranay0302 👋🏻 Thanks a lot for your interest in supervision and drafting this PR. Looks good. Merged!