igoR 1.0.3

• Internal code paths were simplified with AI-assisted refactoring to reduce
  duplicated result handling, status validation and dyad-year joint membership
  recoding.
• igo_dyadic() now computes dyadid with both state codes, as documented.
• User-facing messages were revised for clearer wording and consistent argument
  names.

What's Changed

• Refactor internals and documentation by @dieghernan in #56
• Bump codecov/codecov-action from 6 to 7 by @dependabot[bot] in #57

Full Changelog: v1.0.2...v1.0.3