sites: align SEO meta surface, polish cite pages

[radinhamidi]

Summary

Two threads:

1. SEO meta alignment — the leaderboard's Default.astro had less coverage than the marketing site's (no og:image:alt / og:locale, smaller Twitter card, no jsonLd/ogImage/ogType props). Brought it to parity, then refreshed per-page descriptions on both sites so each page has a unique, keyword-rich <meta name="description"> (~140–180 chars).
2. Cite page polish — SIGIR paper retitled, arXiv link added, both citation boxes now share the same visual height.

Meta changes

• Leaderboard Default.astro: adds og:image:alt, og:locale, summary_large_image Twitter card, meta name="author" / meta name="generator", and new ogImage / ogType / jsonLd props.
• Leaderboard index.astro: emits schema.org/Dataset JSON-LD with sameAs linking to querygym.com, the repo, and both arXiv papers, plus variableMeasured: nDCG@10, R@100, R@1k and keywords for richer search results.
• Marketing site per-page descriptions tightened: about, install, methods, reproducibility, index, and the Default.astro fallback. Header tagline tightened to match the leaderboard's.

Cite changes

• SIGIR Reproducibility Track paper retitled to "A Reproducibility Study of LLM-Based Query Reformulation" on both surfaces.
• arXiv link 2604.27421 added to the SIGIR BibTeX entry (eprint + archivePrefix + url) and surfaced on the card itself via the CitationCard url prop.
• Marketing cite.astro JSON-LD now emits two ScholarlyArticle entries (one per paper) instead of one.
• Both home pages add https://arxiv.org/abs/2604.27421 to their sameAs lists.

CitationCard layout fix

• Card is now a flex column with the top content in its own block and the BibTeX block separated via mt-auto pt-4 — pushes BibTeX to the bottom of the card so both cards' boxes start at the same baseline (grid forces equal card heights).
• BibTeX <pre> gets min-h-56 overflow-auto so both BibTeX boxes have the same visual size regardless of citation length.

Test plan

• /cite on both surfaces shows the new SIGIR title; clicking the URL goes to arXiv 2604.27421
• Both BibTeX boxes on /cite have the same height; longer citation doesn't break layout
• view-source: on /, /about/, /install/, /methods/, /reproducibility/ (marketing) and /, /cite/ (leaderboard) shows updated <meta name="description"> and OG tags
• Google Rich Results test on / (leaderboard) recognizes the Dataset structured data
• Sitemap regenerates on build (1113 URLs on leaderboard, 6 on marketing)

🤖 Generated with Claude Code