chore: import upstream snapshot with attribution

apps/webapp/app/v3/services/concurrencySystemInstance.server.ts

@@ -0,0 +1,15 @@
+import { prisma, $replica } from "~/db.server";
+import { ConcurrencySystem } from "./concurrencySystem.server";
+import { singleton } from "~/utils/singleton";
+
+export const concurrencySystem = singleton(
+  "concurrency-system",
+  initalizeConcurrencySystemInstance
+);
+
+function initalizeConcurrencySystemInstance() {
+  return new ConcurrencySystem({
+    db: prisma,
+    reader: $replica,
+  });
+}