fix: carry click-time pointer position in viewport input message

src/app/mod.rs

@@ -3181,6 +3181,8 @@ pub enum Message {
     /// never fall through and rotate a different camera.
     ViewportClick(Option<codec::Handle>),
     ViewportMove(Point),
+    /// Position recorded by the pointer event itself, not the last hover.
+    ViewportLeftPressAt(Point),
     ViewportLeftPress,
     ViewportLeftRelease,
     ViewportRightPress,