Function err

Core exports - Types, Result<T,E>, errors, and logger Split from index.ts for file size compliance (Issue #285)

err<E>(error: E): Result<never, E>
Creates a failed Result containing the given error.
Type Parameters
- E
  The error value type
Parameters
- error: E
  The error value
Returns Result<never, E>
A Result in the Err state
Example
```
const result = err(new Error('not found'));
if (!result.ok) {
  console.error(result.error.message); // "not found"
}
```
- Defined in packages/nexus-agents/src/core/result.ts:49