Update codec for text fields to align with Jira API changes

## Summary

The io-ts codecs for Jira issue text fields need to be updated to handle changes in the Jira API response format.

## Background

Jira's API has evolved and text fields (such as `description`, `comment.body`, etc.) may now return different formats depending on the Jira instance configuration (e.g., plain text vs. Atlassian Document Format/ADF).

## Tasks

- [ ] Investigate current Jira API text field response formats
- [ ] Update codecs in `lib/src/services/jira.ts` to handle both legacy and new formats
- [ ] Add tests for the new codec handling

## Related Files

- `lib/src/services/jira.ts`
- `lib/src/codecs/`