Group sync previously only ran once at pairing time, so groups created in
WhatsApp afterwards never showed up.
Two complementary fixes:
- 🔄 Refresh button in the groups list view triggers
syncGroupsForAccount() on demand and re-renders the menu
- session.ts now subscribes to Baileys 'groups.upsert' and 'groups.update'
events and re-syncs (debounced 1.5s) so new groups appear without
manual action