fixed typo in core/draw/participant.typ

src/core/draw/participant.typ

@@ -116,7 +116,7 @@
     // Compute lifeline rectangles + destruction positions
     for event in ctx.lifelines.at(p.i).events {
       if event.type == "create" {
-        last-y = line.at(1)
+        last-y = event.y
 
       } else if event.type == "enable" {
         if stack.len() == 0 {