chore: restore Dangerfile for GraphQL compatibility checks

Denys Mishunovrequested to merge
duo-edit-20251128-142936 into main

Description

This MR restores the danger/graphql_compatibility/Dangerfile that was accidentally removed in !2708 (merged).

The Dangerfile provides important automated review guidance for merge requests that modify GraphQL operations, including:

  • Automatic labeling of MRs with GraphQL changes
  • Reminders about fallback behavior for unavailable fields
  • Links to testing documentation
  • Checklist for GraphQL compatibility considerations

Related Issues

Fixes the accidental deletion from !2708 (merged)

How has this been tested?

File content verified against the version before deletion (commit 02110b027a3773b943a601145a57b9d6169ba143).

Merge request reports