ludic.npc (18.2): a person a crowd moves

npc_set_crowd hands a person to a crowd. Its walk no longer steps or asks the way: its want is goal_x / goal_z / goal_speed (0 when it is not walking). npc_moved hands back the crowd's place: position, ground, heading from velocity, gait. Arrival, the act and the give-up after twenty seconds without progress are unchanged. Nothing allocates. npc 16/16.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.npc/defs.ludic

@@ -52,6 +52,10 @@ export property NpcPerson {
   wtx: float = 0.0             # the target that corner was asked for: a new target asks again
   wtz: float = 0.0
   way_t: float = 0.0           # seconds until it asks the way again
+  crowd: bool = false          # walked by the world's crowd (phase 18): it decides, the crowd moves it
+  goal_x: float = 0.0          # where it walks this tick and how fast (0 standing): what a crowd is handed
+  goal_z: float = 0.0
+  goal_speed: float = 0.0
   detours: int = 0
   fails: int = 0
   stall: float = 0.0           # seconds walking without moving