Function cmp_cells 

pub fn cmp_cells(a: &Cell, b: &Cell) -> Ordering

Total order across heterogeneous cells. Numbers compare numerically, timestamps chronologically, everything else lexically by display text.

Same-variant comparisons are allocation-free (&str comparison, not a String clone): this is the M1.8 hot spot — sorting a 50 000-row Text (name) or Status column was cloning two Strings per comparison (~1.7M allocations/query). The heterogeneous fallback still goes through cell_text (numbers/booleans render as text), which is rare in practice and cheap relative to the sort.