Stats() was scanning 5 SQL columns (hit_count, miss_count,
upstream_fetch_count, upstream_fetch_bytes, transform_count) into
mismatched struct fields, causing HitRate to contain the integer
transform_count instead of a 0.0-1.0 ratio.
Simplify the query to only fetch hit_count and miss_count, then
compute TotalItems, TotalSizeBytes, and HitRate correctly.
Fixes#4
