### Is your feature request related to a problem? Please describe.

Progressive image encoding/decoding enables users to already grasp the content of an image before it is fully downloaded on the web. This is very useful, especially over slow internet connections.

The effect is demonstrated in this Youtube video:
https://www.youtube.com/watch?v=UphN1_7nP8U

Image formats that can be encoded progressively include JPEG and the new JPEG XL (JXL) format. JXL isn't supported by all major internet browsers yet, but it has enough browser support to be useful as one of a few format options offered in an HTML picture element.

### Describe the solution you'd like

I would like to be able to use ImageMagick – actually via PHP's Imagick class – to encode JPEG XL (JXL) images progressively.

ImageMagick already can save JXL files, but apparently not with progressive encoding.

### Describe alternatives you've considered

I encode classical JPEGs progressively with ImageMagick and use these. But this is just a fallback, not an equivalent alternative. JXL images offer a significantly better ratio of image quality vs. file size than JPEGs and can hence give a better user experience while causing less internet traffic.

### Additional context

_No response_
Support progressive encoding of JXL
This is a GitHub Issue
repo:ImageMagick
owner:ImageMagick
Title : Support progressive encoding of JXL
Issue date:

--- start body ---
### Is your feature request related to a problem? Please describe.

Progressive image encoding/decoding enables users to already grasp the content of an image before it is fully downloaded on the web. This is very useful, especially over slow internet connections.

The effect is demonstrated in this Youtube video:
https://www.youtube.com/watch?v=UphN1_7nP8U

Image formats that can be encoded progressively include JPEG and the new JPEG XL (JXL) format. JXL isn't supported by all major internet browsers yet, but it has enough browser support to be useful as one of a few format options offered in an HTML picture element.

### Describe the solution you'd like

I would like to be able to use ImageMagick – actually via PHP's Imagick class – to encode JPEG XL (JXL) images progressively.

ImageMagick already can save JXL files, but apparently not with progressive encoding.

### Describe alternatives you've considered

I encode classical JPEGs progressively with ImageMagick and use these. But this is just a fallback, not an equivalent alternative. JXL images offer a significantly better ratio of image quality vs. file size than JPEGs and can hence give a better user experience while causing less internet traffic.

### Additional context

_No response_
--- end body ---

None