ci: pass linkspector config to markdown validation workflow

[Copilot]

This replicates the upstream fix from OAI/OpenAPI-Specification#5368 in this repository. The markdown link-check workflow now explicitly loads this repo’s Linkspector config so existing suppression rules are applied during CI runs.

• Workflow update

  • Updated .github/workflows/validate-markdown.yaml to pass .linkspector.yml into umbrelladocs/action-linkspector@v1.
  • Ensures link checking uses repository-defined behavior instead of action defaults.

• Linkspector configuration wiring

  • Added the missing config_file input to the action step:

  - name: Check links in markdown files
    uses: umbrelladocs/action-linkspector@v1
    with:
      config_file: .linkspector.yml
      reporter: github-check
      fail_level: any
      filter_mode: file