docs: Phase 5 — incident log, maintenance runbook, NUT config archive

beast/nut/upssched.conf: fixed earlyshutdown timer (30s→300s) and added
  cancel rule. Archived post-fix from Beast.
beast/nut/upssched-cmd: archived for reference.

runbooks/phase5-incident-log.md:
  INC-005: NUT upssched earlyshutdown bug — cause, fix, break-test findings.
  INC-001 through INC-004: PBS USB hub/data/re-diagnosis/sdj end-of-life.
  P5-01 through P5-11: pending work queue including Pi4 node-exporter,
  compute5 PCIe PM, PBS recovery gate, qnetd migration, Authelia metrics,
  cert renewal verification, ansible-control disk, Phase 4A resume.

runbooks/maintenance-runbook.md: PBS recovery steps, UPS test procedure,
  cert renewal schedule (May 11/18), Phase 4A per-node procedure, qnetd
  migration, Authelia metrics setup, recurring checklist.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

beast/nut/upssched-cmd

@@ -0,0 +1,20 @@
+#!/bin/sh
+ case $1 in
+       onbatt)
+          logger -t upssched-cmd "UPS running on battery"
+          ;;
+       earlyshutdown)
+          logger -t upssched-cmd "UPS on battery too long, early shutdown"
+          /usr/sbin/upsmon -c fsd
+          ;;
+       shutdowncritical)
+          logger -t upssched-cmd "UPS on battery critical, forced shutdown"
+          /usr/sbin/upsmon -c fsd
+          ;;
+       upsgone)
+          logger -t upssched-cmd "UPS has been gone too long, can't reach"
+          ;;
+       *)
+          logger -t upssched-cmd "Unrecognized command: $1"
+          ;;
+ esac