Compiler Result implementations reject valid variant-changing chains

React version

Current main (2dc7da790d63).

Steps to reproduce

Type-check direct compiler utility chains such as:

Ok(2).andThen(() => Err("failed"));
Ok(2).and(Err("failed"));
Err("failed").or(Ok(4));
Err("failed").orElse(() => Ok(4));

Current behavior

The concrete OkImpl combinators fix the error type to never; ErrImpl.or fixes the success type to never; and ErrImpl.orElse accepts only another ErrImpl. These valid variant-changing chains fail TypeScript compilation with TS2322/TS2345 even though their runtime implementations naturally return the supplied result.

Expected behavior

The concrete implementations should preserve the Rust-style Result combinator behavior and infer the success/error types of the returned result without changing runtime semantics.

Start by locating the OkImpl and ErrImpl Result implementations and type-check the four variant-changing examples in the issue. Update the concrete combinator typings so those examples compile while preserving runtime behavior, then verify the TypeScript errors are gone and existing checks still pass.