NS-23: Fix bump depart — goal Y vs surface footing + arrive by footing

- Ray down at goal xz for destination surface Y; step-off compares two footings.
- Arrive when horiz close and either capsule Y matches goal or underfoot matches
  dest footing (server may send center 0.9 or pick surface 0).

client/scripts/player.gd

@@ -73,11 +73,24 @@ func _floor_y_under_body() -> float:
 	return maxf(y_center, y_lower)
 
 
+## 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:
+	var g: Vector3 = _auth_walk_goal
+	var probe_top: float = maxf(global_position.y, g.y) + 4.0
+	var probe: Vector3 = Vector3(g.x, probe_top, g.z)
+	var y: float = _ray_floor_y_at(probe)
+	if y >= probe_top - 0.05:
+		return g.y
+	return y
+
+
 func _nav_short_step_down_use_goal_direct() -> bool:
 	var floor_y: float = _floor_y_under_body()
-	if _auth_walk_goal.y >= floor_y - STEP_OFF_FLOOR_MARGIN:
+	var dest_floor_y: float = _destination_footing_y()
+	if dest_floor_y >= floor_y - STEP_OFF_FLOOR_MARGIN:
 		return false
-	var drop: float = floor_y - _auth_walk_goal.y
+	var drop: float = floor_y - dest_floor_y
 	if drop < STEP_OFF_MIN_DROP or drop > STEP_OFF_MAX_DROP:
 		return false
 	var hd: float = Vector2(
@@ -105,8 +118,11 @@ 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: float = absf(full_to_goal.y)
+	var vert_err_capsule: float = absf(full_to_goal.y)
-	if horiz_dist <= ARRIVE_EPS and vert_err <= VERT_ARRIVE_EPS:
+	var footing_match: bool = (
+		absf(_floor_y_under_body() - _destination_footing_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
 		_nav_agent.set_target_position(global_position)