feat: publication layer on atlas — turso metadata, zoom-scaled circles, lazy cover images
build-atlas: query turso for publication names/covers, group docs by basePath,
compute centroids, output publications array in atlas.json.
atlas.js: render publication circles scaled by sqrt(count)*zoom (~25 at overview,
hundreds at deep zoom), lazy-load cover images from bsky CDN, fallback letter
circles, name labels at zoom 3+.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>