refactor(xyhandle): use center for to-xy, block updates only if valid

packages/system/src/xyhandle/XYHandle.ts

@@ -161,6 +161,8 @@ function onPointerDown(
     // we don't want to trigger an update when the connection
     // is snapped to the same handle as before
     if (
+      isValid &&
+      closestHandle &&
       previousConnection.toHandle &&
       newConnection.toHandle &&
       previousConnection.toHandle.nodeId === newConnection.toHandle.nodeId &&

packages/system/src/xyhandle/utils.ts

@@ -21,7 +21,7 @@ function getHandles(
     if (node.id === currentHandle.nodeId && type === currentHandle.handleType && handle.id === currentHandle.handleId) {
       excludedHandle = handle;
     } else {
-      const handleXY = getHandlePosition(node, handle);
+      const handleXY = getHandlePosition(node, handle, handle.position, true);
       res.push({ ...handle, ...handleXY });
     }
     return res;