A new report suggests that iPhone 5s supplies will be constrained at launch, as the iPhone 5c will make up the majority of stock at Apple Stores on Friday. Apple is reportedly expecting the space gray iPhone 5s to be the most popular, with fewer silver and gold options in stock. More high-capacity versions of the AT&T 5s models could be available, as compared to Verizon models. It’s also noted that an expected Apple Store app update would…