task: #3586398 Add GitLab issue and merge request templates

Christoph Breidertrequested to merge
issue/ai-3586398:3586398-add-issue-templates into 1.x

Description

Adds structured GitLab issue and merge request templates to guide contributors. Closes #3586398.

The templates were prepared and iteratively refined to align with Drupal's issue etiquette guidelines and Drupal's AI contribution policy. They use GitLab Flavored Markdown hidden comments (<!-- -->) to guide contributors without cluttering the rendered view, and include inline hints for GitLab quick actions (/label, /relate, /blocks, /duplicate, /subscribe) as well as a ddev-based setup snippet for local reproduction.

Note for maintainers: The issue templates reference labels via /label quick actions (~"Bug", ~"Feature", ~"Task", ~"Plan", ~"Support"). These labels need to be created in the project for the quick actions to take effect.

Testing instructions

  1. Navigate to the project's work items and select "New issue"
  2. Verify all five templates appear in the template picker (bug_report, feature_request, task, plan, support_request)
  3. Select each template and confirm structure, quick actions, and hidden comments render correctly
  4. Open a new merge request and verify the Default template is pre-filled

Checklist

  • I have linked the related issue in the MR title or description
  • I have performed a self-review of my own code
  • I have added or updated tests, or explained in the description why this change is not covered by tests
  • I have updated documentation for any new or changed functionality
  • I have written testing instructions and verified them locally
  • I have noted any required post-merge steps (config imports, cache rebuilds, manual changes)
  • This MR contains no breaking API or hook changes, or they are explicitly documented in the description

AI Compliance

Note

Check the one that best describes your usage, or leave all unchecked if AI was not significantly used.

  • AI Assisted Code
    Mainly written by a human; AI used for autocomplete or partial generation under full human supervision.

AI-Generated: Yes (Used Claude to draft and iteratively refine all templates, with full human review and direction throughout.)

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