Prevent production releases blocking master pushes

[Max Harrison (maxharrison)]

The workflow-wide concurrency group held later pushes while a production release waited for approval. Build artifacts also expired after seven days, which prevented delayed releases from deploying.

The workflow now sets job-level concurrency, retains build artifacts for 30 days, and posts a Slack notification when a production release awaits approval.

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Latest commit: a92a7d1

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[ana-maksimovskikh]

Max Harrison (@maxharrison) can we just remove the manual release confirmation bit 🙏
Since a release PR gets manually approved anyway before push, that seems obsolete 👀