srcset missing for header images in new editor

[cathysarisky]

Issue Summary

Image content generated for the new split header layout does not include a srcset. Huge images load by default.

Steps to Reproduce

Create a new page with a header card with the new split layout.
Be lazy and drag a huge image into the image blog, assuming Ghost will resize it.
Publish. Inspect the result. Here's the outcome:

<div class="kg-header-card-content">
                
        <picture><img class="kg-header-card-image" src="https://www.spectralwebservices.com/content/images/2023/08/ghost-website-1.png" alt=""></picture>
    
                <div class="kg-header-card-text ">
                    <h2 id="take-your-ghost-blog-and-newsletter-to-the-next-level" class="kg-header-card-heading" style="color: #FFFFFF;" data-text-color="#FFFFFF"><span>Take your Ghost blog and newsletter to the next level.</span></h2>
                    <h3 id="let-our-team-handle-the-technology-while-you-focus-on-creating" class="kg-header-card-subheading" style="color: #FFFFFF;" data-text-color="#FFFFFF"><span>Let our team handle the technology while you focus on creating.</span></h3>
                    <a href="https://www.spectralwebservices.com/contact/" class="kg-header-card-button " style="background-color: #ffffff;color: #000000;" data-button-color="#ffffff" data-button-text-color="#000000">Contact Us</a>
                </div>
            </div>

Because there's no srcset on image, it loads at 2000px wide. That's silly for anything less than a 4k screen, and really silly for the 1200px wide screen I prefer. My browser actually rendered it at ~500px.

Ghost Version

5.59.1

Node.js Version

Ghost Pro and 16.something

How did you install Ghost?

ghost-cli and ghost pro

Database type

MySQL 8

Browser & OS version

Chrome, recent, windows 10

Relevant log / error output

No response

Code of Conduct

• I agree to be friendly and polite to people in this repository

[witherScript]

@cathysarisky stoked to work on this issue, can you please assign it to me? If there are any specific guidelines or tasks you'd like me to follow outside of the contributions doc, please let me know.

[cathysarisky]

I’m not the Ghost core team, sorry. :)

[witherScript]

@daniellockyer hey, would be stoked to work on this issue, can you please assign it to me? I don't intend to muddy the issue thread

[cathysarisky]

I'll add onto this one instead of opening another bug - these header images are also missing the lazy loading attribute that other body content gets automagically.