feat(stovepipe): support time-based build-slot delay - configuration updates

[mnoah1]

Summary

Intent:

• Make logical admission throttling and failure cooldown configurable per Stovepipe queue.

Changes:

• Add a strict, validated YAML-backed queue configuration store.
• Wire optional QUEUE_CONFIG_PATH loading into the Stovepipe server and local stack.
• Validate configured queues against message-queue tenants and document duration settings.

This change builds on the admission policies introduced by the parent PRs.

Test Plan

Issues