Dozens of startups hope to replace physical cash and credit cards with so-called digital wallets tied to smartphones. But one San Francisco outfit is counting on a smaller payments revolution: simply making a better physical credit card. The company, called Coin, announced Thursday it is making a credit card-sized device that can store information from other credit cards so that it can be used just like the stack of cards crowding wallets for everyday transactions. “The consumer gets to keep their habits and the merchants can keep their habits,” said Kanishk Parashar, Coin’s chief executive, in an interview. Coin looks like a slick plastic credit card, and can swipe like one, but stores account information about multiple credit cards that can be accessed through the single Coin card itself.