Whole-mouth %BOP (getPerioSummary().bopPercent) — drives the
gingivitis fallback when there's no periodontitis-qualifying CAL.
Highest Glickman furcation grade anywhere in the mouth, or null when
nothing is graded (getPerioSummary().maxFurcation) — one of the
stage-III complexity escalation criteria.
Full pure input to derivePerioClassification.