[ffigen] Make regen.dart output visible and include ffinative config

[PranjalManhgaye]

Summary

This PR improves the ffigen regeneration script (test/regen.dart) by making its behavior more complete and observable.

Changes included:

• Adds regeneration for the previously omitted example/ffinative/config.yaml
• Adds explicit logging so it is clear which configs are regenerated, improving debuggability and CI visibility

Verification

Verified locally on Linux by running:

• dart run test/setup.dart
• dart run test/regen.dart

The script now clearly logs each regenerated configuration and successfully regenerates all example and test bindings.

Fixes #862

• [ ✔️] I’ve reviewed the contributor guide and applied the relevant portions to this PR.

[liamappelbe]

The original bug has 2 checklist items:

• Run it on CI, so we know that it works for all 3 host OSes
• Double check that we regen all bindings, not just a subset

This PR doesn't address either of them.

[PranjalManhgaye]

Thanks for pointing it out i was waiting for this clarification i will definitely work on that , Thanks @liamappelbe

[dcharkes]

@PranjalManhgaye Please don't simply use an AI to post superficial PRs and create noise for our team (ditto #2874). If you're interested in contributing actually spend time to understand the issues, play around with the code etc. Make sure you used the packages in your own projects to understand their goal. We've got many external contributors on this repo and love their contributions.