Make "picture" elements have sane output.

[bobdenotter]

Now it's this, in _picture.html.twig:

        <picture class="aspect-ratio-square">
            <source srcset="{{ record|thumbnail(400) }}" media="(min-width: 400px)" />
            <img src="record|thumbnail(400)" alt="(alt goes here)" loading="lazy" />
        </picture>

but, i assume that '400' should be something else

[bobdenotter]

🧹 Spring cleaning! All of these should be finished!