NS-23: Arrival footing uses footprint max_y (avoid false stop on bump lip)

Premature arrival used _floor_y_under_body() vs dest footing; at the rim that
can read floor while xz is already within ARRIVE_EPS, clearing the walk goal.
Match step-down logic: compare destination footing to footprint max_y and
cache footprint scan once per physics frame.

client/scripts/player.gd

@@ -31,6 +31,8 @@ const NEXT_WAYPOINT_MIN_HORIZ_SQ: float = 0.01
 
 var _has_walk_goal: bool = false
 var _auth_walk_goal: Vector3 = Vector3.ZERO
+var _footprint_cache_frame: int = -1
+var _footprint_cache: Dictionary = {}
 
 @onready var _nav_agent: NavigationAgent3D = $NavigationAgent3D
 
@@ -94,7 +96,7 @@ func _floor_y_under_body() -> float:
 
 
 ## One ray pass: max floor Y under footprint + whether any hit is an NS-19 bump (`ns19_bump` group).
-func _footprint_step_down_state() -> Dictionary:
+func _compute_footprint_step_down_state() -> Dictionary:
 	var p: Vector3 = global_position
 	var h: float = STEP_FOOTPRINT_HALF
 	var oxz: Array[Vector3] = [
@@ -140,6 +142,14 @@ func _footprint_step_down_state() -> Dictionary:
 	return {"max_y": best_y, "touches_ns19_bump": on_bump}
 
 
+func _footprint_step_down_state() -> Dictionary:
+	var f: int = Engine.get_physics_frames()
+	if f != _footprint_cache_frame:
+		_footprint_cache = _compute_footprint_step_down_state()
+		_footprint_cache_frame = f
+	return _footprint_cache
+
+
 ## Footing under goal xz (surface Y). Server goal.y may be capsule center (e.g. 0.9) or pick surface
 ## (e.g. 0) — do not compare that directly to `_floor_y_under_body()` (always surface).
 func _destination_footing_y() -> float:
@@ -190,9 +200,12 @@ func _physics_process(_delta: float) -> void:
 	var full_to_goal: Vector3 = _auth_walk_goal - global_position
 	var horiz_dist: float = Vector2(full_to_goal.x, full_to_goal.z).length()
 	var vert_err_capsule: float = absf(full_to_goal.y)
-	var footing_match: bool = (
-		absf(_floor_y_under_body() - _destination_footing_y()) <= VERT_ARRIVE_EPS
-	)
+	var dest_foot_y: float = _destination_footing_y()
+	var fp: Dictionary = _footprint_step_down_state()
+	var max_foot_y: float = float(fp["max_y"])
+	# Same lip issue as step-off: `_floor_y_under_body()` can read floor early and match `dest_foot_y`
+	# while xz is within ARRIVE_EPS — false “arrived”, goal clears. Use footprint max_y.
+	var footing_match: bool = absf(max_foot_y - dest_foot_y) <= VERT_ARRIVE_EPS
 	if horiz_dist <= ARRIVE_EPS and (vert_err_capsule <= VERT_ARRIVE_EPS or footing_match):
 		velocity = Vector3.ZERO
 		_has_walk_goal = false