refactor: corner reads via Element::corner_style (cce-ui 6bd batch 2)

corner_radius/rounded_corners left the Element trait; the aggregate loops
read both through the single corner_style() pair now. Behavior-preserving.

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_018u7qTwzX95dd5ysAkaSCLk

 src/renderer.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/renderer.rs b/src/renderer.rs
index fb20d7a..16ac22a 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -23,7 +23,7 @@ fn collect_window_child(
     texts: &mut Vec<TextTuple>,
 ) {
     let (cx, cy, cw, ch) = w.rect();
-    let child_rounded = w.rounded_corners() != (false, false, false, false);
+    let child_rounded = w.corner_style().1 != (false, false, false, false);
     for (qx, qy, qw, qh, qc) in w.all_quads(ctx) {
         if child_rounded && (qx - cx).abs() < 0.1 && (qy - cy).abs() < 0.1 && (qw - cw).abs() < 0.1 && (qh - ch).abs() < 0.1 {
             continue;