fix: floor-aligned spawn, remove double jump, enable crouch speed

debug/test_level_builder.gd

@@ -94,7 +94,7 @@ func _build_lighting() -> void:
 func _build_player() -> void:
 	var player := CharacterBody3D.new()
 	player.name = "Player"
-	player.position = Vector3(0, 1.7, 8)
+	player.position = Vector3(0, 1.4, 8)
 	add_child(player)
 	var shape := CollisionShape3D.new()
 	shape.shape = CapsuleShape3D.new()