NEON-29: Hysteresis for nav column steering (walk ping-pong)

Single-radius switch at DIRECT_APPROACH_RADIUS let horiz_dist cross every
frame between direct-to-goal and nav-path steering, flipping velocity ~180°.
Schmitt band NAV_COLUMN_STEER_ENTER/EXIT with latched _walk_nav_column_steering;
reset on new goal, snap, arrival, clear.

client/scripts/player.gd

@@ -16,6 +16,12 @@ const FLOOR_ANGLE_LOOSE_TICKS_AFTER_STOP: int = 96
 const ARRIVE_EPS: float = 0.35
 const VERT_ARRIVE_EPS: float = 0.055
 const DIRECT_APPROACH_RADIUS: float = 0.85
+## Hysteresis for nav-path column steering (see `_physics_process`). At exactly
+## [member DIRECT_APPROACH_RADIUS] the old test flipped every frame: path nudges
+## tangentially → [code]horiz_dist[/code] crosses the radius → direct vs path
+## alternates → velocity sign flips (Jolt ping-pong while [code]has_goal[/code]).
+const NAV_COLUMN_STEER_ENTER_DIST: float = 0.74
+const NAV_COLUMN_STEER_EXIT_DIST: float = 0.97
 const FLOOR_SNAP_MOVING: float = 0.32
 ## Idle floor snap length (stronger to pin rim contacts).
 const FLOOR_SNAP_IDLE: float = 0.11
@@ -76,6 +82,8 @@ var _debug_last_idle_xz: Vector2 = Vector2.INF
 var _debug_idle_heartbeat: int = 0
 var _debug_last_transform_xz: Vector2 = Vector2.INF
 var _debug_trace_frame: int = 0
+## True while we use [method _set_horizontal_velocity_from_nav_path_or_goal] for vertical routing.
+var _walk_nav_column_steering: bool = false
 @onready var _nav_agent: NavigationAgent3D = $NavigationAgent3D
 
 
@@ -95,6 +103,7 @@ func set_authoritative_nav_goal(world_pos: Vector3) -> void:
 	_step_assist_active = false
 	_idle_anchor_active = false
 	_idle_manual_correction_ticks = 0
+	_walk_nav_column_steering = false
 	_nav_agent.set_target_position(world_pos)
 
 
@@ -105,6 +114,7 @@ func clear_nav_goal() -> void:
 	_step_assist_active = false
 	_idle_anchor_active = false
 	_idle_manual_correction_ticks = 0
+	_walk_nav_column_steering = false
 	_nav_agent.set_target_position(global_position)
 
 
@@ -141,6 +151,7 @@ func snap_to_server(world_pos: Vector3) -> void:
 	_step_assist_active = false
 	_idle_anchor_active = false
 	_idle_manual_correction_ticks = 0
+	_walk_nav_column_steering = false
 	_nav_agent.set_target_position(settled)
 	reset_physics_interpolation()
 
@@ -674,6 +685,7 @@ func _physics_process(delta: float) -> void:
 		_step_assist_active = false
 		_idle_anchor_active = false
 		_idle_manual_correction_ticks = 0
+		_walk_nav_column_steering = false
 		_nav_agent.set_target_position(global_position)
 		_physics_idle_tick(delta)
 		if _stable_idle_support():
@@ -708,7 +720,13 @@ func _physics_process(delta: float) -> void:
 		_auth_walk_goal.y > feet_y + DESCEND_GOAL_Y_MARGIN
 		or _auth_walk_goal.y < feet_y - DESCEND_GOAL_Y_MARGIN
 	)
-	if needs_vertical_routing and horiz_dist <= DIRECT_APPROACH_RADIUS:
+	if not needs_vertical_routing:
+		_walk_nav_column_steering = false
+	elif horiz_dist <= NAV_COLUMN_STEER_ENTER_DIST:
+		_walk_nav_column_steering = true
+	elif horiz_dist >= NAV_COLUMN_STEER_EXIT_DIST:
+		_walk_nav_column_steering = false
+	if needs_vertical_routing and _walk_nav_column_steering:
 		_set_horizontal_velocity_from_nav_path_or_goal(want_goal_h)
 	else:
 		_set_horizontal_velocity_toward(_auth_walk_goal, want_goal_h)