Pure charting-order helper for the full-mouth perio grid's keyboard
auto-advance (PerioChart.tsx) — given the cell just charted, returns the
NEXT cell in charting order (see the order table comment above), or
null at the very end (last lingual gm site of the last tooth in the
arch order). An unrecognized cur (a site string not in PERIO_SITES
or a row other than "pd"/"gm") also returns null. Never mutates
state — a plain-object round trip, trivially unit-testable in isolation.
Pure charting-order helper for the full-mouth perio grid's keyboard auto-advance (PerioChart.tsx) — given the cell just charted, returns the NEXT cell in charting order (see the order table comment above), or
nullat the very end (last lingual gm site of the last tooth in the arch order). An unrecognizedcur(a site string not in PERIO_SITES or arowother than "pd"/"gm") also returnsnull. Never mutates state — a plain-object round trip, trivially unit-testable in isolation.