chore(examples): carve_union_demo takes its size from CCE_DEMO_W/H

So the window doubles as a movable/resizable probe in a shadow session
(used to check grid snapping edge by edge).

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

 examples/carve_union_demo.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/examples/carve_union_demo.rs b/examples/carve_union_demo.rs
index 93951a2..18154b1 100644
--- a/examples/carve_union_demo.rs
+++ b/examples/carve_union_demo.rs
@@ -40,8 +40,10 @@ impl Application for DemoApp {
         WindowSettings {
             title: "carve union demo".into(),
             app_id: "cce-carve-union-demo".into(),
-            width: 760,
-            height: 560,
+            // CCE_DEMO_W / CCE_DEMO_H override the size — handy when the
+            // window doubles as a snap/tiling probe in a shadow session.
+            width: std::env::var("CCE_DEMO_W").ok().and_then(|v| v.parse().ok()).unwrap_or(760),
+            height: std::env::var("CCE_DEMO_H").ok().and_then(|v| v.parse().ok()).unwrap_or(560),
             fullscreen: false,
             min_size: None,
         }