Documentation lost when re-exporting from @typeberry/lib

## Problem

When re-exporting types and utilities from `@typeberry/lib` in jammin-sdk, the documentation is removed, making them harder to discover for developers.

## Context

This issue was identified during PR review where helper functions were added to work around the documentation loss problem. The underlying issue with re-exports should be addressed to improve developer experience and discoverability.

## References

- PR #106: https://github.com/FluffyLabs/jammin/pull/106
- Discussion: https://github.com/FluffyLabs/jammin/pull/106#discussion_r2811650930
- Reported by: @DrEverr

## Expected Outcome

Re-exported items from `@typeberry/lib` should retain their original documentation to enable proper IDE completion and developer discoverability.