[LalitNarayanYadav]

Resolves #9328

Changes:

• paletteLerp() returned undefined outside p5.strands because the strands override returned early without calling the original CPU implementation. The override now saves the original paletteLerp and delegates to it when no strands context is active, the same pattern lerpColor uses.
• Adds a regression test that calls paletteLerp() outside strands and checks the interpolated color. It fails without the fix (undefined) and passes with it.
• Strands behavior and the argTypes metadata are unchanged, and the existing paletteLerp and argTypes tests still pass.

This regression came from #8817. Targeting the 2.4 milestone.

PR Checklist

• npm run lint passes
• Unit tests are included / updated