chore: root_plate_* — cce-ui 7a-2 caller migration

Mechanical rename onto cce-ui's canonical root-plate getters
(cce-ui@c8e0ab3, RFC Phase 7a); behavior unchanged, same config slots.

 src/main.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 02be5b7..e5be7aa 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -632,9 +632,9 @@ impl ColorApp {
             let backplate = {
                 let mut c = cce_ui::color::page_low_color();
                 if c[3] > 0.001 {
-                    c[3] = cce_ui::color::active_backplate_opacity();
+                    c[3] = cce_ui::color::root_plate_opacity();
                 }
-                let radius = cce_ui::colors::backplate_corner_radius();
+                let radius = cce_ui::colors::root_plate_corner_radius();
                 (c, 0.0, 0.0, self.width as f32, self.height as f32, radius.max(0.0), (radius > 0.1, radius > 0.1, radius > 0.1, radius > 0.1))
             };
             if self.window_focused {