Allow switching between ordinary and oversized notehead variants

Issue type

Engraving bug (incorrect score rendering)

Description with steps to reproduce

MuseScore fails to honor the explicit stem attachment points defined in the glyphsWithAnchors section of SMuFL metadata JSON files for third-party fonts.
This causes ugly stem alignment issues with specific third-party fonts like MTF-Cadence (where upward stems render shifted towards the center of the notehead).

Steps to Reproduce

1. Install a third-party SMuFL font.
2. Open the font's metadata .json file and manually change the glyphsWithAnchors coordinates for noteheadHalf to absurdly extreme values.
3. Open MuseScore Studio and create a new score.
4. Go to Format → Style and load the modified SMuFL font.
5. Input a half note into the score.

Expected behaviour

The stem should be heavily offset and detached from the notehead, following the high coordinate values injected into the JSON.

Actual behaviour

The stem remains locked in its original position.

Supporting files, videos and screenshots

https://github.com/user-attachments/assets/9c540002-61f6-444d-bcc2-825763b94a85

In the attached video, I tested two different fonts. Eugene can be downloaded for free at https://mikkopatama.com/eugenefont/, while MTF-Cadence is a commercial font. Please note that the beam thickness was altered solely to demonstrate that MuseScore is indeed interpreting the font's JSON metadata file but ignoring the stem anchor adjustments.

In which versions of MuseScore Studio is this issue present?

4.6.1 (4.6.0 was not tested) - 4.7.4 and 4.7-/master-nightlies

Regression

I was unable to check

Operating system

Windows 11

Additional context

A similar issue was previously reported in #29734 and closed as completed in #29838, but this bug still exists.

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible