release: prepare Quarto-Needs 0.2.0

[lsbjordao]

This is the consolidated 0.2.0 release-preparation PR. It supersedes #34, #35, #36 and #38 and includes the original version-consistency work from #39.

Included consolidation

• complete multilingual GitHub Pages artifact deployment, replacing generated-HTML commits to main;
• frozen historical release surface for v0.1.1, verified against the immutable annotated Git tag;
• migration release-gate documentation derived from migration_cli.SOURCES, including ReqIF;
• refreshed Failure Gallery coverage for QND005 versus valid custom attributes;
• one version contract across Python, Quarto extension copies, starter, self-hosted example, VS Code package metadata and lockfile.

0.2.0 version bump

The release candidate now declares 0.2.0 consistently in pyproject.toml, quarto_needs.__version__, all shipped Quarto extension copies, the starter, the self-hosted installed extension, VS Code package.json, and both root entries in package-lock.json. The lockfile was regenerated by npm under a guarded temporary workflow that refused unrelated changes; that workflow was removed before the final branch was squashed to one clean commit.

Release-history policy

CHANGELOG.md intentionally keeps these changes under [Unreleased] until an actual v0.2.0 tag exists. release-surfaces/0.2.0.json must only be created once the immutable tag commit is known; the new release-surface-history workflow would otherwise correctly reject a fabricated anchor.

Manual repository setting before merge

Please set Settings → Pages → Build and deployment → Source → GitHub Actions. The GitHub connector available in this session does not expose that administration mutation. After that switch, the merged CI workflow will deploy the complete rendered site through the github-pages environment.

The branch is based on the current main commit after the legacy self-hosted-example publication commit, so no mainline work is dropped.