fix(release): target formatted release commits

[JSONbored]

Summary

• make release publishing target the final release-ready commit when the only post-release commit formats the generated changelog
• keep the original release commit target when arbitrary later commits exist

What changed

• adds a publish-target helper for release commits
• updates aio_fleet release publish to use that helper
• adds regression coverage for format-only follow-up commits and real post-release changes

Why

Release preparation needed follow-up changelog formatting commits. Without this, formal GitHub Releases would point at the earlier release PR merge instead of the final commit that actually passed central checks and produced packages.

Validation

• uv run --with pytest pytest tests/test_release.py tests/test_cli.py tests/test_registry.py
• uv run --with pytest pytest
• trunk check --show-existing --all --no-progress --color=false