Thailand is poised to close most of its cannabis shops by the end of the year under sweeping new rules requiring retailers to operate as licensed medical clinics with on-site doctors – a move that could roll back much of the country’s brief experiment with decriminalised marijuana.The new regulations – set to be enforced by the end of the year – will leave around 2,000 of Thailand’s estimated 18,000 cannabis shops in operation, a Ministry of Public Health official said on Tuesday.That is...