A veteran West Marin postmaster will retire this week, capping a 29-year career that spanned the Grand Canyon to Stinson Beach. Jim Harvey, who worked in Stinson for the past decade after leaving his post in Point Reyes Station, experienced historic changes in mail delivery and manned the front lines at critical moments. Even on his way into retirement, his depot has been put to the test with the inheritance of Bolinas mail services, which…