chore(release): automate versioning + CHANGELOG beyond manual 0.1.0 tags

[ulises-jeremias]

Problem

CPA is stuck on a single 0.1.0 release with a thin root CHANGELOG. CNA uses Changesets → Version Packages PR → npm publish with rich per-package changelogs (create-awesome-node-app@0.13.1, @create-node-app/core@0.7.5).

Without release automation, users cannot trust upgrade paths and maintainers will keep hand-tagging forever.

Proposal

Pick one approach and document it:

1. Changesets (closest to CNA), or
2. hatch version / uv workspace bump + conventional changelog

Acceptance criteria

• Decision recorded in docs/VERSIONING.md (update if needed)
• PR-based version bump flow (bot or documented human checklist)
• CHANGELOG entries generated/required per release for CLI + core
• Tag → GitHub Release → PyPI remains green
• At least one post-0.1.0 release exercises the path (can be 0.1.1 docs/ci-only)

References

• CNA: .github/workflows/publish.yml + changesets
• Current: Release workflow skeleton (tag → GitHub Release) #52, chore(release): first PyPI publish of create-awesome-python-app #148