Add LintLang linter plugin

[roli-lpci]

Summary

• add the released LintLang 0.6.0 Python-runtime linter plugin
• emit its native SARIF diagnostics for supported Markdown, YAML, JSON, and Python instruction/config inputs
• include clean and finding fixtures plus the required README entry

Validation

• npm test -- linters/lintlang --runInBand --verbose
• npm test -- tests/repo_tests --runInBand --verbose
• trunk check --filter=definition-checker --output=json

The command intentionally preserves LintLang's SARIF distinction between scanner findings and input-error invocation notifications.

[trunk-io]

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[roli-lpci]

/trunk merge

[trunk-io]

An error occurred while submitting your PR to the queue: Only users that are a part of this repo's Trunk organization or have write permissions to the repo can submit a PR to the queue

[roli-lpci]

This PR looks code-complete and mergeable, but CI has not actually run yet: both "Pull Request" and "Code Scanning - Action" are sitting at action_required, which needs a maintainer to approve workflow runs for an outside contributor. Separately, /trunk merge from a non-member cannot submit to the merge queue. Could a repository member approve the workflow runs, and if the results look good, submit it to the queue?