Nell's fight-field animations land; fight portraits stay mounted

Nell picks up her own idle, selected, attack, hit, KO, and KO-loop sprite sheets on the fight field, driven through the same animation state machine as Maya. The shared sprite path was generalised away from Maya-specific naming so the next hero slots in without another rewrite. Nell's field sheets run at 14fps, with per-sheet calibration so the frames line up between the selection pose, the attack windup, and the hit reaction.

Hero and enemy portrait stacks now stay mounted across the planning ↔ playout switch instead of unmounting and rebuilding when the phase changes. The rebuild used to force the portrait art to reload on slower or uncached devices, which left the stacks blank during the first beats of playout. The stacks now just fade out during playout and come back in cleanly when planning returns.

On the way in: the opening cutscene renders its static first frame instead of stuttering through the video on slow connections, the title and walking and base scenes wait until their art is actually painted before revealing instead of filling in in front of the player, and base scenes background-warm triggers that haven't activated yet so something like the Nell-after-tutorial trigger never flashes unloaded the first time it appears. Versions 5.0.3 and 5.0.4 cut to staging web over the course of the day.