Implement correct SMuFL stems for renaissance/medieval noteheads

Issue type

Engraving bug (incorrect score rendering)

Bug description

Hi ! I'm in the process of transcribing some good ol' Franco-Flemish Renaissance polyphony, which requires me to use long notes with square heads.
The "Alt. Brevis" notehead style is actually really great in that regard, but i noticed a tiny issue with the longa and its stem:

By default, the width of the stem is 0.1, which is appropriate with the default notehead style (the one that looks like this "IIOII"), but doesn't work with the larger square notehead.
Of course, stem width can be edited so that shouldn't be a problem, but getting it exactly right happens to be impossible !

A stem width of 0.15 is almost perfect, with a minuscule scuffed joint !
I tried to offset the note by 0.01, or using a width of 0.14 or 1.6, but nothing works !

The easiest fix i can think of would be to make the "Alt. Brevis" square note's line very slightly thicker to match a 0.15 stem width

I made a little picture to illustrate the issue !

and here's a little reference with some unrelated nerdy comments

This is a very small issue but it is very extremely important because one of my teacher is a world class expert in ancient music notation and i'm sneakily trying to convert him to musescore by casually having the most perfectly rendered transcriptions ever

Steps to reproduce

-Make a 4/1 measure and write a longa (= 2 brevis = 4 whole notes)
-change the notehead style to "alt. brevis"
-try to get the stem and the note to smoothly connect
-impossible, can't be done

Screenshots/Screen recordings

No response

MuseScore Version

4.x

Regression

I don't know

Operating system

Windows 11

Additional context

No response