Part of #430.

New standalone npm package providing a CLI to validate scope42 workspaces in CI or pre-commit hooks.

Tasks

• Scaffold packages/scope42-lint, depending on @scope42/data
• CLI entrypoint scope42-lint [path] that loads scope42.yaml and validates every item file's frontmatter against the Zod schemas
• Validate relation IDs (causedBy, resolves, modifies, creates, supersededBy, assesses) resolve to existing items of the allowed type
• Validate filename/ID matches the type's idPattern from the config
• Validate required H1/title heading is present in the body (format-agnostic: first non-blank line of body matches a heading syntax)
• Warn (not fail) on smells: empty body, modified < created, orphaned items with no relations, unknown frontmatter keys
• Human-readable output (default) with file:line references; machine-readable --format=json
• Exit codes: 0 clean, 1 warnings, 2 errors
• Fixture-based unit tests under packages/scope42-lint/test/fixtures/ covering Markdown and AsciiDoc inputs
• Publish as @scope42/lint with clear npx usage
• Document a GitHub Actions snippet for CI integration