Business and municipal leaders recently joined Gov. Dannel P. Malloy and Stamford Mayor David Martin ”” sharing scissors, center ”” to mark the completion of 66 Summer St. in Stamford, a 15-story mixed-use building that contains more than 200 rental residential units and 6,600 square feet of retail space. The project is run by builder A.P. Construction, with multiple Stamford offices, Associated A.P. Construction, with a 66 Summer St. address, and national real estate developer Trinity Financial. Apartment sizes span studios to two-bedroom/two bathroom duplex units.