NS-23: Revert global gravity; use step-off-only descend vy

Project gravity while walking made motion worse (jitter, floor fights).
Restore horizontal-only seek everywhere except the short step-down bypass,
where a fixed downward speed helps clear NS-19 bump lips without affecting
normal nav or idle air state.

client/scripts/player.gd

@@ -2,8 +2,8 @@ extends CharacterBody3D
 
 ## NS-23: Follow server move target on walkable geometry.
 ##
-## Horizontal seek sets `velocity.x`/`z` only. On floor `velocity.y` is cleared; in air project
+## Horizontal velocity toward nav waypoint or goal; `velocity.y` stays 0 except a short **step-off**
-## gravity applies so walking off bumps/steps can descend (vy was never forced to 0 while airborne).
+## nudge (see `_nav_short_step_down_use_goal_direct`) so NS-19 bumps can drop without full gravity.
 ## Move **legality** is server MoveCommand only — not reimplemented here.
 ##
 ## Nav for detours; short local step-down (feet vs goal Y, not body origin) may bypass waypoints.
@@ -19,6 +19,8 @@ const STEP_OFF_MIN_DROP: float = 0.055
 const STEP_OFF_MAX_DROP: float = 0.24
 const STEP_OFF_MAX_HORIZ: float = 3.0
 const FLOOR_PROBE_BODY_Y_OFFSET: float = -0.55
+## Downward vy only while step-off bypass is active (not global gravity).
+const STEP_OFF_DESCEND_SPEED: float = 1.6
 ## If next waypoint is within this xz of us, steer to goal (rim / underfoot waypoints).
 const NEXT_WAYPOINT_MIN_HORIZ_SQ: float = 0.01
 
@@ -106,33 +108,13 @@ func _set_horizontal_velocity_toward(point: Vector3) -> void:
 	var dh: Vector3 = Vector3(point.x - pos.x, 0.0, point.z - pos.z)
 	if dh.length_squared() < 1e-10:
 		dh = Vector3(1.0, 0.0, 0.0)
-	var h: Vector3 = dh.normalized() * MOVE_SPEED
+	velocity = dh.normalized() * MOVE_SPEED
-	velocity.x = h.x
+	velocity.y = 0.0
-	velocity.z = h.z
 
 
-func _apply_vertical_velocity_for_floor_or_gravity(delta: float) -> void:
+func _physics_process(_delta: float) -> void:
-	if is_on_floor():
-		velocity.y = 0.0
-		return
-	var gmag: float = float(ProjectSettings.get_setting("physics/3d/default_gravity", 9.8))
-	var gvec: Variant = ProjectSettings.get_setting(
-		"physics/3d/default_gravity_vector", Vector3(0.0, -1.0, 0.0)
-	)
-	if gvec is Vector3:
-		velocity += (gvec as Vector3) * gmag * delta
-	else:
-		velocity.y -= gmag * delta
-
-
-func _physics_process(delta: float) -> void:
 	if not _has_walk_goal:
-		if is_on_floor():
+		velocity = Vector3.ZERO
-			velocity = Vector3.ZERO
-		else:
-			velocity.x = 0.0
-			velocity.z = 0.0
-			_apply_vertical_velocity_for_floor_or_gravity(delta)
 		move_and_slide()
 		return
 
@@ -152,13 +134,12 @@ func _physics_process(delta: float) -> void:
 	var nav_map: RID = _nav_agent.get_navigation_map()
 	if NavigationServer3D.map_get_iteration_id(nav_map) == 0:
 		_set_horizontal_velocity_toward(_auth_walk_goal)
-		_apply_vertical_velocity_for_floor_or_gravity(delta)
 		move_and_slide()
 		return
 
 	if _nav_short_step_down_use_goal_direct():
 		_set_horizontal_velocity_toward(_auth_walk_goal)
-		_apply_vertical_velocity_for_floor_or_gravity(delta)
+		velocity.y = -STEP_OFF_DESCEND_SPEED
 		move_and_slide()
 		return
 
@@ -174,5 +155,4 @@ func _physics_process(delta: float) -> void:
 		else:
 			_set_horizontal_velocity_toward(_auth_walk_goal)
 
-	_apply_vertical_velocity_for_floor_or_gravity(delta)
 	move_and_slide()