Function drive_render_targets 

pub fn drive_render_targets(
    targets: ResMut<'_, RenderTargets>,
    images: ResMut<'_, Assets<Image>>,
    nodes: Query<'_, '_, &ComputedNode>,
    cameras: Query<'_, '_, (&PortalCamera, &mut Camera)>,
)

Drive resolution and the snapshot lifecycle each frame:

• For Resolution::Auto targets, size the texture to the binding portal’s laid-out physical size (quantized to [SIZE_STEP]) and mark dirty on change.
• For each PortalCamera, set is_active: always on for RenderMode::Live; on for one frame for a dirty RenderMode::Snapshot, then off.