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_dashboard_coalescing.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,label: String) -> void:
@@ -35,6 +36,10 @@ func run() -> void:
 	await process_frame;await process_frame
 	clock.advance_minutes(3)
 	expect(runtime.create_snapshot()==after,"coalesced display preserves deterministic simulation replay")
-	main.queue_free()
+	var _audio_cleanup_final: Dictionary = await FixtureCleanup.free_owner_and_wait(self, main)
+	if not bool(_audio_cleanup_final.get(&"passed", false)):
+		push_error("Ordinary fixture audio cleanup failed: %s" % str(_audio_cleanup_final))
+		quit(96)
+		return
 	await process_frame;await process_frame
 	print("Dashboard coalescing: %d checks, %d failures" % [checks,failures]);quit(failures)