ea195993de
In-flight coalescing already dedups identical misses, but acceptance still lacked a gated test (without a hold, waiters can become sequential HITs after the first fill) and the Quick check metrics table omitted cache_coalesced. Add steamcache/coalesce_test.go: N concurrent identical GETs share one upstream fill (leader MISS, waiters HIT-COALESCED) and a 5xx sibling. Document cache_coalesced next to the other hit/miss fields. Fixes #35