Tesla's app went seven years without a version for folding phones, and then Tesla shipped one two days before Apple's first folding iPhone hit stores. The reason is the same reason half the apps on your phone look a little off on any screen they weren't built for. Before a company builds a new layout, somebody runs the math on how many customers will actually see it. For seven years, the math on Android foldables kept coming up short. They're still only about 2% of phones sold. And that 2%…