Spiral Pool v2.7.1

• fix(celebrate): read the LED with the dialect Avalon MM firmware accepts (3cfe072)
• fix(celebrate): identify Avalon MM firmware, add dark-when-idle LED state (ea26751)
• fix(sentinel): wire the ZMQ connected gauge, key the alert on health status (2548b81)
• docs(contributors): record provenance for the celebration and auto-restart fixes (a335bd3)
• fix: point the test-celebration button at the RGB script, hold the auto-restart cooldown on failure (c4d652c)
• release: v2.7.1 — Spiral Citadel (4758fa9)