ClickBench as a Dive

A port of the ClickBench site (benchmark.clickhouse.com) that reads every result from md:clickbench_site, refreshed daily from ClickBench main by the clickbench-site-refresh Flight, and can include our own results not yet merged upstream (e.g. PR #2319). Same filters, scoring, ranking and detailed comparison as the site, plus a per-system history view.