Splitfile Specific Skin overrides

[jeremysmitherman]

Problem description

Users can set default skin in settings, but splitfile editor should also have a selected skin override

• Falls back to default if not available
• Is cleared in exported versions of the splitfile.

Proposed solution

• Make the skin selector a reuseable component
• Add it to the split file editor
• Save it as a field in the splitfile
• If the selected skin is unavailable or broken, fall back to default skin in config
• When exporting splitfile, clear this field.

Alternatives considered

No response

Additional context

No response