✨ Expose camera field of view

### Prerequisites - [x] I have searched [existing issues](https://github.com/mrousavy/react-native-vision-camera/issues?q=is%3Aissue) for a similar request. ### What problem are you trying to solve? In vision camera v5, the camera's displayableZoomFactor is exposed, which allows the UI to display the camera's magnification factor. However, camera UIs will often want to display the camera's actual focal length in mm rather than as an arbitrary zoom multiplier. Deriving this requires the camera's FOV to be exposed. <img width="603" height="531" alt="Image" src="https://github.com/user-attachments/assets/0d38f9d1-212d-49da-b5ae-9a071eb25ab2" /> ### Proposed API / solution The `CameraController` should expose an additional readonly number representing the camera's field of view in degrees. ### Alternatives considered _No response_ ### Platforms this should target Both ### Would you be willing to contribute this? No, I'm requesting only. ### Additional context https://developer.apple.com/documentation/avfoundation/avcapturedevice/format/videofieldofview ### Submission - [x] I described the problem, not just the solution. - [x] I wrote this request in my own words. I did not paste AI-generated proposals.