Note

Low Risk
Low risk CI-only change that affects Buildkite job scheduling/ordering but not application runtime behavior. Main risk is miscomputed priority (e.g., failing PR number extraction/GraphQL query) leading to default priority 0 and unexpected build ordering.

Overview
Adds merge-queue-aware scheduling for Buildkite runs by introducing a pipeline priority derived from MERGE_QUEUE_PRIORITY.

The GitHub workflow now extracts the PR number from the merge-queue ref, queries GitHub’s GraphQL API for the PR’s merge queue position, converts it to a negative priority (earlier in queue = higher priority), and passes it to Buildkite via build_env_vars.

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