fix(core): keep nx watch process alive while listening for file changes

The watch command was exiting immediately after registering the file watcher
because the registerFileWatcher() function completed and there was nothing
keeping the Node.js event loop alive.

Unlike the main daemon socket which has a keep-alive timeout, the file watcher
socket doesn't generate any timers or pending promises that would prevent the
process from exiting.

Fix: Add an infinite promise after registering the file watcher. This keeps
the event loop alive indefinitely while the file watcher callbacks handle
incoming file change events. The process will exit cleanly when:
- User presses Ctrl+C (signal handler)
- The file watcher connection closes (callback receives 'closed' event)

Author: FrozenPandaz

packages/nx/src/command-line/watch/watch.ts

@@ -241,4 +241,9 @@ export async function watch(args: WatchArguments) {
     }
   );
   args.verbose && output.logSingleLine('watch process waiting...');
+
+  // Keep the process alive while watching for file changes
+  // The file watcher callbacks will handle incoming events
+  // The process will exit when Ctrl+C is pressed or if the connection closes
+  await new Promise(() => {});
 }