deselect cards when placing cards fails

src/main.zig

@@ -582,6 +582,8 @@ pub fn doSelectOrPlace(pressed: bool) !void {
             new_snapshot.selected_card = null;
             try history.append(seizer.platform.allocator(), new_snapshot);
             hovered_card = @intCast(indexOfTopOfStack(new_snapshot.getDeck(hovered_deck.?)));
+        } else {
+            snapshot.selected_card = null;
         }
     }
 }