feat: Add mdformat plugin

[marschattha]

Generated using add plugin claude command in #2636

[github-actions]

No issue mentions found. Please mention an issue in the pull request description.

Use GitHub automation to close the issue when a PR is merged

[Copilot]

Pull request overview

This PR adds a new mdformat plugin to enable CommonMark-compliant Markdown formatting in Qlty. The plugin integrates mdformat as a Python-based formatter with standard test fixtures and documentation.

Changes:

• Added plugin configuration defining mdformat as a Python-based formatter for Markdown files
• Created test infrastructure with fixtures and snapshot expectations
• Added comprehensive README with usage instructions and licensing information

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
qlty-plugins/plugins/linters/mdformat/plugin.toml	Defines the mdformat plugin configuration with runtime, versions, and formatter driver settings
qlty-plugins/plugins/linters/mdformat/mdformat.test.ts	Implements standard linter test integration using the test framework
qlty-plugins/plugins/linters/mdformat/fixtures/basic.in.md	Provides test fixture with intentionally malformatted Markdown for testing
qlty-plugins/plugins/linters/mdformat/fixtures/snapshots/basic_v1.0.0.shot	Contains expected test output snapshot for version 1.0.0
qlty-plugins/plugins/linters/mdformat/README.md	Documents plugin usage, configuration options, and external links

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[qltysh]

Coverage Impact - ubuntu-latest

This PR will not change total coverage.

🚦 See full report on Qlty Cloud »

🛟 Help

• Diff Coverage: Coverage for added or modified lines of code (excludes deleted files). Learn more.

• Total Coverage: Coverage for the whole repository, calculated as the sum of all File Coverage. Learn more.

• File Coverage: Covered Lines divided by Covered Lines plus Missed Lines. (Excludes non-executable lines including blank lines and comments.)

  • Indirect Changes: Changes to File Coverage for files that were not modified in this PR. Learn more.

[qltysh]

Coverage Impact - macos-15

⬇️ Merging this pull request will decrease total coverage on main by 0.01%.

🚦 See full report on Qlty Cloud »

🛟 Help

• Diff Coverage: Coverage for added or modified lines of code (excludes deleted files). Learn more.

• Total Coverage: Coverage for the whole repository, calculated as the sum of all File Coverage. Learn more.

• File Coverage: Covered Lines divided by Covered Lines plus Missed Lines. (Excludes non-executable lines including blank lines and comments.)

  • Indirect Changes: Changes to File Coverage for files that were not modified in this PR. Learn more.