added CSG toolkit

addons/csg_toolkit/scripts/patterns/csg_pattern.gd

@@ -0,0 +1,19 @@
+@tool
+@abstract
+class_name CSGPattern
+extends Resource
+
+## Base pattern interface. Subclasses implement _generate(RepeaterContext) returning Array[Vector3].
+
+# Common interface call
+func generate(ctx: Dictionary) -> Array:
+	# ctx expected keys: repeat: Vector3i, spacing: Vector3, rng: RandomNumberGenerator, step_spacing: Vector3, user: Node (repeater)
+	return _generate(ctx)
+
+func _generate(_ctx: Dictionary) -> Array:
+	return []
+
+func get_estimated_count(ctx: Dictionary) -> int:
+	# Default: fallback to generating (may be overridden for performance/accuracy)
+	var arr = _generate(ctx)
+	return arr.size()