Fixes file uploader showing invalid file modal just one time

[kart-u]

Summary

Closes #5521
Due to the file input not being reset in Uploader.vue, the modal exhibited buggy behavior where a alert modal for particular invalid file would only appear once when doing consecutive upload for the same file.
This has been fixed by adding a resetFileInput() call on KModal submit

References

bandicam.2025-11-06.03-41-14-269.mp4

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Reviewer guidance

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[MisRob]

Hi @kart-u, thanks for another contribution! We will assign a reviewer.

I've just merged your other #5522 - could you rebase this PR on top of the latest unstable so we can see the new diff only?

[kart-u]

@MisRob I have rebased the branch onto the current unstable as you requested.

On a side note, I’m currently deepening my understanding of the codebase, so if there are any medium to hard issues in future, please consider me for them I’d love to contribute 😊

[MisRob]

Thanks @kart-u, occasionally there is a gap like now, but typically few new 'help wanted' issues of various complexity are added each week, so you can keep an eye on the list.