restructured code in separated files

src/participant.typ

@@ -0,0 +1,17 @@
+#let _par(name, display-name: auto, start-at: 0) = {
+  return ((
+    type: "par",
+    name: name,
+    display-name: if display-name == auto {name} else {display-name},
+    start-at: start-at
+  ),)
+}
+
+#let _exists(participants, name) = {
+  for p in participants {
+    if name == p.name {
+      return true
+    }
+  }
+  return false
+}