feat: Level loading from TOML asset

- Fixed detect_interactions system
- Added test for deserializing asset with plugin

src/layout/stairs.rs

@@ -38,7 +38,6 @@ pub fn on_stairs_interact(
         return;
     };
     let Ok(mut player_transform) = player_query.single_mut() else {
-        error!("Player is not single");
         return;
     };