style: render top model notice as a bounded card inside canvas

Author: kitlangton

src/app_window.rs

@@ -3403,17 +3403,20 @@ impl AppWindow {
                 .justify_center()
                 .flex_shrink_0()
                 .px_8()
-                .py_4()
-                .bg(rgb(SURFACE))
-                .border_b_1()
-                .border_color(rgb(LINE))
+                .pt_6()
                 .child(
                     div()
                         .w_full()
                         .max_w(px(PANE_CONTENT_WIDTH))
+                        .px_4()
+                        .py_3p5()
                         .flex()
                         .items_center()
                         .gap_4()
+                        .rounded(px(PANEL_RADIUS))
+                        .border_1()
+                        .border_color(rgb(LINE))
+                        .bg(rgb(SURFACE))
                         .child(
                             div()
                                 .flex_1()