feat(eng): add contributor reporting and management scripts

- Add eng/README.md documenting maintainer utilities
- Add eng/contributor-report.mjs for generating contributor reports
- Add eng/add-missing-contributors.mjs for automating contributor additions
- Add eng/utils/graceful-shutdown.mjs for script lifecycle management
- Update eng/update-readme.mjs with minor fixes
- Update package.json with new contributor scripts

Generated-by: GitHub Copilot <copilot@github.com>
Signed-off-by: Ashley Childress <6563688+anchildress1@users.noreply.github.com>

eng/utils/graceful-shutdown.mjs

@@ -0,0 +1,60 @@
+/**
+ * Lightweight graceful shutdown helper for one-off scripts.
+ *
+ * Call setupGracefulShutdown('script-name') early in your script to attach
+ * signal and exception handlers that exit the process cleanly.
+ *
+ * @param {string} name - Human readable name for log messages
+ * @param {{exitCode?:number}} [opts]
+ * @returns {() => void} teardown function to remove handlers (useful in tests)
+ */
+export const setupGracefulShutdown = (name, { exitCode = 1 } = {}) => {
+  let _shuttingDown = false;
+
+  const cleanup = (signal) => {
+    if (_shuttingDown) return;
+    _shuttingDown = true;
+    console.log(`\n🛑 ${name}: received ${signal}, shutting down gracefully...`);
+    // Best-effort cleanup: keep this short and synchronous
+    try {
+      // Place for lightweight cleanup tasks if needed in future
+    } catch (e) {
+      console.error(`${name}: error during shutdown cleanup:`, e);
+    }
+
+    // Exit with a non-zero code to indicate abnormal termination
+    try {
+      process.exit(exitCode);
+    } catch (e) {
+      // process.exit may not be desirable in some test harnesses; swallow errors
+      console.warn(`${name}: process.exit failed:`, e?.message);
+    }
+  };
+
+  const onSigInt = () => cleanup('SIGINT');
+  const onSigTerm = () => cleanup('SIGTERM');
+  const onSigHup = () => cleanup('SIGHUP');
+  const onUncaught = (err) => {
+    console.error(`${name}: Uncaught exception:`, err);
+    cleanup('uncaughtException');
+  };
+  const onUnhandledRejection = (reason) => {
+    console.error(`${name}: Unhandled promise rejection:`, reason);
+    cleanup('unhandledRejection');
+  };
+
+  process.on('SIGINT', onSigInt);
+  process.on('SIGTERM', onSigTerm);
+  process.on('SIGHUP', onSigHup);
+  process.on('uncaughtException', onUncaught);
+  process.on('unhandledRejection', onUnhandledRejection);
+
+  // Return a teardown function useful for tests or if a caller wants to remove handlers
+  return () => {
+    process.removeListener('SIGINT', onSigInt);
+    process.removeListener('SIGTERM', onSigTerm);
+    process.removeListener('SIGHUP', onSigHup);
+    process.removeListener('uncaughtException', onUncaught);
+    process.removeListener('unhandledRejection', onUnhandledRejection);
+  };
+};