vendored bevy_egui and removed legacy code :/

Signed-off-by: Sienna Meridian Satterwhite <sienna@r3t.io>

crates/app/src/camera.rs

@@ -3,6 +3,8 @@
 //! This module handles the 3D camera setup for the cube demo.
 
 use bevy::prelude::*;
+use bevy::camera::RenderTarget;
+use bevy::window::WindowRef;
 
 pub struct CameraPlugin;
 
@@ -17,11 +19,19 @@ impl Plugin for CameraPlugin {
 /// Camera is positioned at (4, 3, 6) looking at the cube's initial position (0,
 /// 0.5, 0). This provides a good viewing angle to see the cube, ground plane,
 /// and any movements.
+///
+/// libmarathon's debug_ui will automatically attach the primary egui context
+/// to this camera via the setup_primary_egui_context_system.
 fn setup_camera(mut commands: Commands) {
     info!("Setting up camera");
 
     commands.spawn((
         Camera3d::default(),
+        Camera {
+            target: RenderTarget::Window(WindowRef::Primary),
+            ..default()
+        },
         Transform::from_xyz(4.0, 3.0, 6.0).looking_at(Vec3::new(0.0, 0.5, 0.0), Vec3::Y),
+        // PrimaryEguiContext will be auto-added by libmarathon
     ));
 }