Support tuning alterations

[kulek1]

Issues

Fixes #

Proposed changes

Checklist

• I consent that this change becomes part of alphaTab under its current or any future open source license
• This PR is linked to an accepted issue (see above)
• Changes are implemented
• New tests were added
• I have read AGENTS.md if an AI helped draft any part of this PR

AI authorship disclosure

• No AI agent authored any part of this PR (description, code, tests, or commit messages)
• An AI agent contributed to this PR. The AI-authored disclosure block
  (alphatab-ai-authored-v1) is present at the top of this body, and I have
  personally reviewed every change and can explain each one

Further details

• This is a breaking change
• This change will require update of the documentation/website

[github-actions]

Thanks for the pull request. Before we dig into the code, a couple of things need addressing in the description:

• Keep the pull request template sections. The description is missing section: Root-cause analysis. Please include it — even a short answer keeps the report actionable.
• Link the issue this addresses. Reference it in the description with Fixes #<n> (or Closes / Resolves) so the change can be traced back to the discussion we agreed on.

If the description isn't updated within 7 days, this pull request will be closed automatically and labeled state-rules-not-followed. Reopen any time — an edit to the description is all it takes.

If an AI helped draft this, AGENTS.md covers the same expectations from the AI side.