refactor: dedupe process-scoped lock maps

src/shared/process-scoped-map.ts

@@ -0,0 +1,12 @@
+export function resolveProcessScopedMap<T>(key: symbol): Map<string, T> {
+  const proc = process as NodeJS.Process & {
+    [symbolKey: symbol]: Map<string, T> | undefined;
+  };
+  const existing = proc[key];
+  if (existing) {
+    return existing;
+  }
+  const created = new Map<string, T>();
+  proc[key] = created;
+  return created;
+}