ci: run PR checks on merge_group so the merge queue works

[sdbondi]

Summary

The repo's main branch ruleset enables a merge queue (SQUASH, ALLGREEN) and requires the Test status check. However, pr-check.yml only triggered on pull_request and workflow_dispatch.

When a PR is added to the queue, GitHub creates a gh-readonly-queue/main/... branch and dispatches a merge_group event. With no workflow listening for that event, the required Test check never runs on the queue branch, so the queue entry sits in AWAITING_CHECKS until the 60-minute timeout — nothing can merge through the queue. (This is exactly what happened to #150, which had to be merged manually.)

Fix

Add the merge_group trigger to pr-check.yml:

on:
  pull_request:
  merge_group:
  workflow_dispatch:

Now the Test (and file licenses) jobs run on the queue branch, the queue sees the required check report green, and merges complete.

⚠️ This PR needs a one-time bypass merge

GitHub only fires merge_group for workflows that exist on the default branch. Since main doesn't yet contain this trigger, the queue still can't validate this PR — it will stall like the others. This PR must therefore be merged once via admin/bypass (org admins have bypass_mode: always on the ruleset). Every PR after this lands on main will merge through the queue normally.

Docs/CI-config only; no application code changes.

🤖 Generated with Claude Code

[gemini-code-assist]

Note

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