Radical protesters played a cat-and-mouse game with police on Sunday as they staged flash-mob “shopping tours”, blocked roads and trashed train stations and mainland-linked shops amid festering anger over the mysterious death of a student.As calls spread online for demonstrators to go on mall marches, scuffles broke out between protesters and police by mid-afternoon in at least seven districts. Large shopping centres in these neighbourhoods were soon swept up in a frenzy of confrontations and…