Site weight and link previews: unsubset fonts, webp og:image #216

What

Two small landing-page and gallery weight and metadata items from the Pages review (#208):

1. Unsubset fonts. Inter regular, medium and bold ship at 109 / 112 / 112 KB (scripts/site/fonts/). JetBrains Mono is 90 KB. That is about 420 KB of the landing page's ~1.3 MB first load. A Latin-only subset (pyftsubset --unicodes="U+0000-00FF,U+2010-2027,U+2190-2193") would typically cut each Inter weight to ~20–30 KB.
2. Social preview image. og:image / twitter:image point to …/gallery/assets/*-hero.webp, with no og:image:width, og:image:height or og:image:alt. Some link-preview scrapers do not render webp. A 1200×630 PNG or JPEG card would be the safe choice. The gallery index's og:image is simply the first entry's hero (swatch-grid).

Neither is broken; both are cheap wins.