Various warning fixes

[gwen-lg]

Description

fixe some warning from rustc and clippy

Motivation and Context

clean the code and part of work for avoid failed jobs reported by check workflow : https://github.com/noahbald/oxvg/actions/runs/19668140313/job/56330008578

How Has This Been Tested?

cargo check/clippy + CI

Types of changes

Checklist:

• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

[noahbald]

Thanks Gwen for the cleanup, you've been super helpful!

[noahbald]

Don't worry about the deprecated warnings, I still want them for this release but they will be removed in the next

[noahbald]

Thanks Gwen, are you happy for me to merge this?

[gwen-lg]

Yes you can merge this to at least reduce the number of lints to fix