refactor(lock): centralize lock utility functions

- Moved `withTimeout` to `src/utils.mjs` and exported it.
- Updated `src/lock-utils.mjs` to re-export `withTimeout` and `mergeRelayList` from `src/utils.mjs`.
- Removed duplicate local definitions of `withTimeout` and `mergeRelayList` in `src/lock-ops.mjs` and `src/lock-publisher.mjs`.
- Fixed `test/utils.test.mjs` to import `mergeRelayList`.
- Verified all tests pass with `npm test`.

Co-authored-by: PR0M3TH3AN <[email protected]>

src/utils.mjs

@@ -55,3 +55,13 @@ export function ensureDir(dir) {
 export function relayListLabel(relays) {
   return relays.join(', ');
 }
+
+export function withTimeout(promise, timeoutMs, timeoutMessage) {
+  let timeoutHandle;
+  const timeoutPromise = new Promise((_, reject) => {
+    timeoutHandle = setTimeout(() => reject(new Error(timeoutMessage)), timeoutMs);
+  });
+  return Promise.race([promise, timeoutPromise]).finally(() => {
+    if (timeoutHandle) clearTimeout(timeoutHandle);
+  });
+}