Save The Tree implementation and acceptance work in progress

Preserve production code, regression fixtures, audio assets and provenance, test infrastructure, and the original-completion plan and progress ledger. Final game and Windows acceptance remain pending; excluded local artifacts and native experiments are not part of this snapshot.

tests/ui/test_anri_recruitment.gd

@@ -1,4 +1,5 @@
 extends SceneTree
+const FixtureCleanup := preload("res://tests/helpers/ui_audio_fixture_cleanup.gd")
 var checks := 0
 var failures := 0
 func expect(ok: bool, message: String) -> void:
@@ -101,5 +102,9 @@ func run() -> void:
 		await process_frame; await RenderingServer.frame_post_draw
 		expect(root.get_texture().get_image().save_png(ProjectSettings.globalize_path("res://artifacts/facility-dimensions-2026-09-29/anri-floor-assigned.png")) == OK, "capture recruited Anri")
 	SaveService.delete_save(path)
-	main.queue_free(); await process_frame
+	var cleanup: Dictionary = await FixtureCleanup.free_owner_and_wait(self, main)
+	if not bool(cleanup.get(&"passed", false)):
+		push_error("Anri recruitment ordinary owner cleanup failed: %s" % str(cleanup))
+		quit(96)
+		return
 	print("Anri recruitment UI: %d checks, %d failures" % [checks,failures]); quit(failures)