chore(ci): add merge queue triggers

[Copilot]

Merge queue entries were not starting the required CI workflow, so protected branches using merge queues could stall waiting for checks that never reported. This updates the main CI workflow to run on merge-group refs in addition to the existing PR and push paths.

• What changed

  • Added the merge_group trigger to /home/runner/work/cli/cli/.github/workflows/ci.yml.
  • Scoped it to checks_requested, which is the event GitHub emits when a PR is added to the merge queue.

• Behavioral impact

  • The existing required CI jobs now run for merge queue validation without changing their job graph or publish conditions.
  • Required checks can report against merge-group SHAs, allowing branch protection with merge queues to progress normally.

• Workflow snippet

  on:
    pull_request:
      branches: [main]
    merge_group:
      types: [checks_requested]