make mobile view-only? or support a better placement method + touch screen pan/z...

https://github.com/mosure/bevy_r_place/blob/eec59b7273102be2e0e3e1318b2e680893a47a00/src/viewer.rs#L109

```rust

}


// TODO: make mobile view-only? or support a better placement method + touch screen pan/zoom
fn setup_ui(
    canvas: Res<ChunkedCanvas>,
    mut commands: Commands,

```