Two fixes from manual interactive verification after iteration-3:
1. Head 90° CCW off → removed sprite_rot=-90 from head bone. The
v0.3.3 sprite_rot fix was based on misobservation: at that point
the persistent-state-rate-limit bug was active and head was
wiggling within ±10° of an arbitrary initial direction, perceived
as 90° CW off. With v0.3.2+ persistent-state fix and v0.4.0 slerp,
head rotates correctly when sprite-natural-face is -Y (matching
body-sprite convention).
2. Legs walked in inverted sector → signed_angle_2d cross-component
was using Y-up math convention but Sporel screen-coords are Y-down.
With Y-down, what's CCW in math is CW visually. Flipping the cross
sign aligns sector selection: body up + player walks right → CW
visually → walk_right_lower (was wrongly returning walk_left).
Front/back leg-anchor issue (#3 from user report) deferred — likely an
optical-overlap artifact from rotated body sprite + world-frame leg
positions, will reassess after #1+#2 fixes are visually verified.
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