web: serve editorial images at quality 90 and add sizes to image blocks

web/next.config.mjs

@@ -25,6 +25,9 @@ const nextConfig = {
   images: {
     remotePatterns: remotePatterns(),
     formats: ["image/avif", "image/webp"],
+    // 90 is for editorial images (ImageFigure); AVIF at the default 75 is
+    // visibly soft on photos. Qualities not listed here are rejected.
+    qualities: [75, 90],
     minimumCacheTTL: 7 * 24 * 60 * 60, // 7 days
     // smoke tests build in production mode against a mock CMS on 127.0.0.1;
     // the flag is serialized into the build, so it must be set at build time