Sigma SD & DP cameras: White Balance and/or color calibration are off for DNGs

Describe the bug

With the default settings for white balance and color calibration, colors are off for Sigma DNG images shot with a foveon sensor (i.e. Sigma SD & DP series).

The effect can be avoided when setting color calibration to 'bypass' and white balance to 'as shot' (==first 'camera'-icon in the 'white balanace' tab). But unfortunately the last step (set white balance to 'as shot') can't be saved in a camera specific default because only temperature and tint are saved in the default.

These facts make processing Sigma SD&DP images a royal pain.

Steps to reproduce

1. import a Sigma DNG image
2. == yuck, everything's green and yellow.

Expected behavior

Darktable should either display correct colors from the beginning, OR save the fact that white balance is set to "as shot" in the white balance default if the camera icon was clicked.

Logfile | Screenshot | Screencast

Commit

as far as I can tell this problem has always been there

Where did you obtain darktable from?

GitHub nightly

darktable version

4.7.0+852~gf0c81ac018

What OS are you using?

Mac

What is the version of your OS?

MacOS 14

Describe your system?

MacBook Pro M2 14"

Are you using OpenCL GPU in darktable?

Yes

If yes, what is the GPU card and driver?

M2

Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip

No response

Start by reproducing the issue with a Sigma SD or DP DNG and inspect how the white balance and color calibration defaults are applied. Trace the camera-specific default handling, especially whether the "as shot" white balance choice is persisted; done means Sigma DNGs receive correct colors by default or preserve that choice in the camera default.