const STATS_THRESHOLD: usize = _; // 65_536usizeExpand description
Number of pushes a from-scratch container observes before it turns its gathered stats into a safe codec.
A safe codec has at most 256 - SAFE_TAG_BASE (= 134) dictionary slots per
column, so we only need to identify ~134 genuinely-popular values. The
MisraGries summary retains up to 2 * k (= 1024) distinct candidates
between tidies and reduces to k (= 512), comfortably more than 134, so the
threshold just needs to be large enough that heavy hitters accumulate counts
well above 1 before we freeze the codec. 64Ki pushes gives that headroom while
keeping the pre-codec (uncompressed) window short.