macos: restore overlay close button

apps/macos/Sources/Clawdis/VoiceWakeOverlay.swift

@@ -571,6 +571,26 @@ private final class ClickCatcher: NSView {
     }
 }
 
+private struct CloseHoverButton: View {
+    var onClose: () -> Void
+
+    var body: some View {
+        Button(action: self.onClose) {
+            Image(systemName: "xmark")
+                .font(.system(size: 12, weight: .bold))
+                .foregroundColor(Color.white.opacity(0.85))
+                .frame(width: 22, height: 22)
+                .background(Color.black.opacity(0.35))
+                .clipShape(Circle())
+                .shadow(color: Color.black.opacity(0.35), radius: 6, y: 2)
+        }
+        .buttonStyle(.plain)
+        .focusable(false)
+        .contentShape(Circle())
+        .padding(6)
+    }
+}
+
 private struct CloseButtonOverlay: View {
     var isVisible: Bool
     var onHover: (Bool) -> Void