Bug Report: stopAutoSync() incorrectly clears _pausedAutoSyncUserIds, preventing auto-sync restoration after pause/resume

Hi Shreemanarjun,

I've found a critical bug in the Datum library's sync management that prevents auto-sync timers from being properly restored after calling pauseSync() followed by resumeSync().

When pauseSync() is called:

1. It saves active auto-sync user IDs to _pausedAutoSyncUserIds
2. It calls stopAutoSync() without parameters
   
   The issue is in stopAutoSync() method:

// In the no-parameter path of stopAutoSync():
if (_isSyncPaused) {
  _pausedAutoSyncUserIds.clear();  // ← This line clears the list!
}

This means that when resumeSync() tries to restore auto-sync timers:

for (final userId in _pausedAutoSyncUserIds) {
  startAutoSync(userId);
}
// _pausedAutoSyncUserIds is now empty, so no timers are restored!

Steps to Reproduce



1. Start auto-sync for one or more users
2. Call pauseSync()
3. Call resumeSync()
4. Expected: Auto-sync timers should resume
5. Actual: No auto-sync timers are restored

Thank you for your excellent library!

Start by tracing pauseSync(), stopAutoSync(), and resumeSync() in the Dart sync-management code, focusing on how _pausedAutoSyncUserIds is handled. Reproduce the pause/resume sequence with one or more users and verify that auto-sync timers are restored afterward.