v1.0.2

Fix Result type preservation for downstream clients.

• Result is now abstract with map, bind, alt, or_else returning Result
• Ok/Err override all methods to stay in Result land (no degradation to Either)
• TryAsync overloads for correct async function inference
• Validated.__add__ returns Validated (not Applicative)
• Abstract to_result/to_result_or on Validated base

Downstream clients no longer need any ty suppressions.