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You are given daily device activity data from Resmed devices. Write a PostgreSQL query to return, for each region and calendar date, the number of active devices and the rolling 7-day average of active devices. Treat a device as active on a date when it has at least one activity event that day. Your result should include dates with zero active devices, and the 7-day average should be calculated over the current date plus the previous 6 dates within each region.
