Fixes #7643 This commit address the issue with 3 minor fixes: 1. Initialize ghostty lib before app start, or global allocator will be null. 2. `addSublayer` should be called on CALayer object, which is the property 'layer' of UIView 3. According to apple's [document](https://developer.apple.com/documentation/metal/mtlstoragemode/managed?language=objc), managed storage mode is not supported by iOS. So always use shared mode. FYI, another [fix](https://github.com/mitchellh/libxev/pull/204) in libxev is also required to make iOS app work.