fix(ui): Flux 2 Model Manager default settings not showing Guidance

[blessedcoolant]

Summary

The model defaults panel for Flux 2 models were showing CFG Scale and Rescale CFG sliders instead of showing the Guidance sliders which is incorrect. This also fixes users now being able to set default Guidance for Flux 2 Klein models.

QA Instructions

1. Go to Model Manager.
2. Select Flux 2 Klein Model.
3. Check if "Guidance" shows up and not CFG Scale or Rescale.
4. Set it to 1 or whatever and save setting.
5. Go to Generation tab and press the "star" to see if default guidance is set correctly.
6. Profit.

Merge Plan

Pretty straight forward. Just merge.

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• ❗Changes to a redux slice have a corresponding migration
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)

[Pfannkuchensack]

Thank you!