Add new music tracks to the sound directory

- Added cosmic_unicorns.ogg
- Added funky_eldritch.ogg
- Added meditative_beings.ogg
- Added owniverse_main_theme.ogg

These tracks enhance the audio experience of the project.

tests/test_world_indicators.gd

@@ -133,7 +133,7 @@ func run() -> void:
     Parameters.advance(source, world.state, rules, E.of("1.0e12"))
     check((E.ge(world.state.trends.Integration, 0) and E.lt(world.state.trends.Integration, 1)), "Very large intervals finish with a valid trend fraction")
     check(E.ge(world.state.world_parameters.Agg, 1), "Repeated integration events cannot reduce aggression below the scale")
-    var payload: Dictionary = {"format_version": 3, "app_version": "test", "ui": {"current_page": 1}, "state": world.state}
+    var payload: Dictionary = {"format_version": 4, "app_version": "test", "ui": {"current_page": 1}, "state": world.state}
     var manager: Node = root.get_node("SaveManager")
     check(E.eq(manager.validate_data(payload), ""), "New parameters and trends pass save validation")
     var old: Dictionary = payload.duplicate(true)