.NET SDK guidance

[FracturedCode]

I have read the infisical .NET SDK documentation, and I have a few questions I could not find answered in examples, documentation or a cursory inspection of the .NET SDK code.

1. Is the client thread safe?
2. What should the lifetime of the client be? I want to know whether I should be constructing a new client often or share a singleton for the runtime of my application (indefinite), or something in between. This probably depends a lot on how the authentication works behind the scenes.
3. There are some environment variables specified in the documentation for Universal Auth. If these are set, do you have to read these in manually and set the Auth property in ClientSettings, or will the client read the environment variables automatically?
4. Would you be open to an async implementation of the library? I'm going to write one anyway so may as well contribute it back if you're interested.