Fixed a bug where tab groups could split into duplicate copies across different windows, sometimes with tabs missing from one of the copies. This happened when a sync was triggered while another was still running (e.g. the automatic weekly sync overlapping with a manual "Sync now"). Syncs are now serialized so only one runs at a time per profile.

Fixed a bug where customers who bought a lifetime licence after their trial ended could still see a "Trial ended" error and have syncing blocked, even though their account was correctly licensed. Syncing now correctly recognizes an active licence in every case.