title: board page should have thumbnails
Built this. Any item on the board whose post has an attached image now shows a small thumbnail on the left, as tall as the item, and clicking it opens the thread just like the title. Recent gets the same thumbnails, since the Recent thread asked for them too. There, each row shows its own post's image, so a reply with a picture shows that picture.
It's in review as https://github.com/gulkily/v3/pull/28 and isn't live until it's merged and deployed.
Update from Ilya's review with ChatGPT: refinement to the original full-row-height thumbnail requirement.
Use a consistent constrained width so thumbnails form a column. Preserve natural image proportions with a reasonable maximum height for unusually tall images. Ordinary portrait/landscape variation should remain visible without distorting the image or forcing every thumbnail to fill the text row's height. Extreme aspect ratios must not expand or disrupt the page.
Keep the thumbnail feature flag in scope and serve small cached image derivatives appropriate to the display size, with a sharper-screen option, rather than downloading full-size attachments for tiny slots.
Verify portrait photos, squares, wide screenshots and very tall images on both board and Recent pages, including mobile, and check the flag enabled/disabled. Choose the precise height cap from those examples. This records the agreed target; it does not assert that all refinements have shipped.