Add bison model to default editor palette and object catalog

scripts/smoke_test_bison_model.gd

@@ -0,0 +1,37 @@
+extends SceneTree
+## Test loading and instantiating bison.glb prop
+
+func _init() -> void:
+	print("=== Smoke Test: Bison Model ===")
+	var path := "res://assets/props/bison.glb"
+	if not FileAccess.file_exists(path):
+		printerr("FAIL: bison.glb does not exist on disk at ", path)
+		quit(1)
+		return
+
+	var res := load(path)
+	if res == null:
+		printerr("FAIL: Could not load ", path)
+		quit(1)
+		return
+
+	print("PASS: Loaded PackedScene: ", res)
+	if res is PackedScene:
+		var inst = (res as PackedScene).instantiate()
+		if inst == null:
+			printerr("FAIL: Could not instantiate bison scene")
+			quit(1)
+			return
+		print("PASS: Instantiated bison: ", inst.name, " (", inst.get_class(), ")")
+		_print_node(inst, 0)
+		inst.queue_free()
+
+	print("=== Bison Model Smoke Test Passed ===")
+	quit(0)
+
+
+func _print_node(n: Node, depth: int) -> void:
+	print("  ".repeat(depth), "- ", n.name, " [", n.get_class(), "]")
+	for c in n.get_children():
+		_print_node(c, depth + 1)
+