chore(release): simplify workflow — bump-level dispatch, drop testpypi/preflight/smoke

[antosubash]

Summary

• Replace the release workflow's version + target inputs with a bump choice (patch / minor / major, default patch) plus an optional version override. A new resolve job computes the next version from framework/core/pyproject.toml and shares it with every downstream job.
• Delete the preflight job, both smoke jobs, and every testpypi code path (input option, environment, conditional gates, repository-url conditional).
• Stop running pr.yml on pushes to main — the preflight gate was its only consumer, so push runs were pure waste.
• Harden publish-npm: verify the tarball's package.json is scoped to @simple-module-py/<matrix.package> before publishing, and prefix the path with ./ so npm doesn't parse dist-npm/simple-module-py-ui-0.0.1.tgz as a GitHub user/repo shorthand (root cause of the recent publish failure).
• Rewrite docs/release.md to match the new flow.

Why

The TestPyPI rehearsal, preflight gating, and post-release smoke were all optional safety nets that rarely caught anything and made the dispatch UI noisy. The bump-level dispatch matches how I actually pick versions; keeping an explicit override preserves the escape hatch for prereleases. The npm guard fixes a real failure from the last release attempt.

Test plan

• Dispatch manually with default inputs (bump: patch, no version) once merged and verify resolve picks the expected next version
• Dispatch with an explicit version (e.g. prerelease tag) and confirm the override path
• Confirm publish-npm matrix no longer triggers the ssh://git@github.com/dist-npm/... error