feat(plugin): add terrain3d plugin installation

addons/terrain_3d/utils/transform_changed_notifier.gd

@@ -0,0 +1,16 @@
+# Copyright © 2023-2026 Cory Petkovsek, Roope Palmroos, and Contributors.
+# Transform Changed Notifier for Terrain3D
+@tool
+extends Node3D
+
+signal transform_changed
+
+
+func _ready() -> void:
+	assert(Engine.is_editor_hint())
+	set_notify_transform(true)
+
+
+func _notification(what: int) -> void:
+	if what == NOTIFICATION_TRANSFORM_CHANGED:
+		transform_changed.emit()