Add retained paints and shared text selection

app-rust/tests/top_edge.rs

@@ -3,7 +3,7 @@ use iris::harness::Harness;
 use iris::prelude::*;
 
 const HEADER_H: f32 = 300.0;
-const HEADER: UiColor = UiColor::new(28, 28, 34, 255);
+const HEADER: Srgba8 = Srgba8::new(28, 28, 34, 255);
 
 fn opened() -> (Harness, ai_app::ui::TranscriptScreen) {
     let mut h = Harness::new(phone_size(), PHONE_SCALE);