refactored groups, separators and delays

src/core/draw/delay.typ

@@ -0,0 +1,27 @@
+#import "../utils.typ": get-ctx, set-ctx
+#import "../../cetz.typ": draw
+
+#let render(delay) = get-ctx(ctx => {
+  let y0 = ctx.y
+  let y1 = ctx.y - delay.size
+  for (i, line) in ctx.lifelines.enumerate() {
+    line.lines.push(("delay-start", y0))
+    line.lines.push(("delay-end", y1))
+    ctx.lifelines.at(i) = line
+  }
+  if delay.name != none {
+    let x0 = ctx.x-pos.first()
+    let x1 = ctx.x-pos.last()
+    draw.content(
+      ((x0 + x1) / 2, (y0 + y1) / 2),
+      anchor: "center",
+      delay.name
+    )
+  }
+  ctx.y = y1
+  set-ctx(c => {
+    c.y = ctx.y
+    c.lifelines = ctx.lifelines
+    return c
+  })
+})