[Improvement] Use mouse pos as origin when pressing +/-

[alexmk92]

Currently, when you zoom in or out with + or - it will zoom into the centre of the canvas. This PR aligns the zoom behaviour so we can drill in based on the mouses origin.

This also enables zooming around the minimap as the origin with +/- so you can quickly navigate the profile

Its made it much easier for me to zoom in on points of interest, I hope its of use downstream, but totally understand if this is too much of a niche change!

Screenshare.-.2025-10-09.1_05_34.PM.mp4

[alexmk92]

@jlfwong apologies for the Actions approval spam - this is my first Open Source contribution, I didn't realise subsequent pushes would queue many actions without cancelling the previous one.

I've no additional changes to make, so this is "Ready for Review" if there's any interest in merging it downstream.

Thanks again for this project, its aided my local profiling efforts immensely.

[coveralls]

coverage: 43.454% (-0.1%) from 43.602%
when pulling 113d34a on alexmk92:main
into e5786f9 on jlfwong:main.

[jlfwong]

Pretty slick! Thanks for the upgrade