useRdIntraMode property
When true, the keyframe per-MB intra-mode picker replaces the
hand-tuned _yModeBias/_uvModeBias arrays in
intra_mode_select.dart with per-mode Lagrangian biases
(sadPerBit16 * kfModeBitCost(probs, mode)) >> 8 derived from the
active kfYModeProb/kfUvModeProb tables. Requires useMvRateCost
(otherwise sadPerBit16 is 0 and the picker is a no-op). Default
false keeps existing behaviour byte-identical.
Implementation
final bool useRdIntraMode;