style-audit: declare this surface's opt-out from the standard root plate

cce-ui's scripts/style-audit checks that every app stands on the
standard root plate; the lock screen is a black surface carrying one
card plate by design, and the comment says so, so the audit lists it as
an opt-out rather than as off-standard.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

 src/main.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/main.rs b/src/main.rs
index 33a2350..e411055 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -286,6 +286,7 @@ impl AppState {
     /// The lock screen itself: an opaque ground, a centred card, the password
     /// well and its bullets, and one status line.
     fn build_scene(&self, w: f32, h: f32) -> (cce_ui::scene::paint::DisplayList, Vec<Label>) {
+        // style-audit: opt-out the lock screen is a black surface carrying one card plate
         let mut pc = cce_ui::scene::paint::PaintCtx::new();
         let mut labels = Vec::new();