og:image pointed at the 1200px WebP dialog variant: no declared size,
a 16:9 frame that link previews crop unpredictably, and WebP isn't
rendered by every preview client. The alt text was just the site name.
Photo variants now include <slug>-<hex>-og.jpg, a centre crop to
1200x630, and the head declares its type and size. Migration 013 adds
photo_og so rows built before this keep using the WebP until "Rebuild
resized photos" is run. The alt text names the pictured datacenter and
city. resize and the new og_crop share one convert call.
Assisted-by: Claude:opus-5
