LONDON — It began with a bet. The 23-year-old Dieter Rams was working as a junior in a Frankfurt architect’s office when a colleague spotted an ad in a local newspaper for an “in-house architect” at a company they knew nothing about. He dared Mr. Rams to apply to see which of them would be chosen. Mr. Rams, now 79, won, and took the job. His new employer was Braun, an electrical appliance manufact