JXL color management incorrectly applied

[PaulCoddington]

Describe the bug

JXL files are displayed dark, high contrast and oversaturated (severe).

To Reproduce

Steps to reproduce the behavior:

1. Set monitor mode/profile (Display P3).
2. Prepare PNG image (16-bit Display P3).
3. Convert PNG image to JXL with cjxl (same folder).
4. Open PNG image (PicView).
5. Use arrow keys to swap between JXL and PNG.

Expected behavior

• Expect PNG and JXL to look identical.*

* Assuming lossless and/or perceptually lossless conversion was used.

Additional context

In Affinity, digiKam and XnViewMP:

• PNG/JXL are displayed correctly (identical).
• PNG/JXL are both reported as 16-bit Display P3.