chore: migrate release pipeline from @jscutlery/semver to nx release

[lukascivil]

Objective

Replace the @jscutlery/semver + ngx-deploy-npm release pipeline with Nx's built-in nx release, consolidating version bump, changelog, git tag/push, GitHub release, and npm publish into a single command while preserving the existing conventional-commits-driven, per-project semver behavior.

What was done

• Configured nx.json → release with projects: ["json-difference", "json-difference-cli"], projectsRelationship: "independent", releaseTagPattern: "{projectName}-{version}", per-project changelogs with GitHub release creation, and git commit/tag/push enabled.
• Mapped conventional commit types under release.conventionalCommits.types so feat → minor, fix/docs/chore/refactor → patch, keeping parity with the prior @jscutlery/semver behavior.
• Removed the version, github, and npm executor targets from libs/json-difference/project.json and libs/json-difference-cli/project.json — nx release now drives these.
• Rewrote package.json release / release:dry-run scripts to call yarn nx release (with --dry-run when previewing) and dropped @jscutlery/semver, ngx-deploy-npm, and conventional-changelog-conventionalcommits from devDependencies (with matching yarn.lock cleanup).
• Updated .github/workflows/release-and-publish.yml to invoke yarn nx release --yes with explicit --projects= and --dry-run flag handling, and removed the now-unused nrwl/nx-set-shas step.
• Refreshed the "Release flow" section of CLAUDE.md to describe the new nx release pipeline, the tag pattern, and the semver-bump mapping.

Test plan

• Run yarn release:dry-run --projects=json-difference locally and confirm the planned version bump, changelog, and tag match expectations.
• Trigger the release-and-publish workflow with dry_run=true and name=all, verify it runs nx release --yes --dry-run cleanly with no publish side effects.
• Trigger the same workflow with dry_run=true and name=json-difference, confirm the --projects=json-difference flag is forwarded.
• After merge, run a real release on one package and verify CHANGELOG.md, the {projectName}-{version} git tag, the GitHub release, and the npm publish all succeed end-to-end.