Move window controls into the title bar

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/main.rs

@@ -31,6 +31,14 @@ fn main() -> iced::Result {
                 size: Size::new(1120.0, 720.0),
                 min_size: Some(Size::new(760.0, 480.0)),
                 icon: Some(app_icon()),
+                // The title bar is ours: content runs to the top edge and the
+                // native traffic lights float over it.
+                #[cfg(target_os = "macos")]
+                platform_specific: window::settings::PlatformSpecific {
+                    title_hidden: true,
+                    titlebar_transparent: true,
+                    fullsize_content_view: true,
+                },
                 ..Default::default()
             });
             (App::load(main_window), open.map(Message::WindowOpened))