docs: modernize power resilience plan and shutdown orchestration with NFS-safe tiering, direct Gotify alerts, and Longhorn clean detach

scripts/nut_notify.sh

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+#!/bin/bash
+# /usr/local/bin/nut-notify.sh
+# Emergency power notification script for Network UPS Tools on Snarfnet
+set -euo pipefail
+
+EVENT_TYPE="${1:-$NOTIFYTYPE}"
+UPS_NAME="${UPSNAME:-snarf-ups}"
+TIMESTAMP=$(date '+%Y-%m-%d %H:%M:%S')
+
+# Internal Gotify VIP endpoint (bypasses Authentik Forward Auth and NPM)
+GOTIFY_INTERNAL_URL="http://140.44.4.70:8090/message"
+GOTIFY_APP_TOKEN="${GOTIFY_APP_TOKEN:-A4uN4fEmErGeNcYtOkEn}"
+
+send_gotify() {
+    local title="$1"
+    local message="$2"
+    local priority="$3"
+    
+    curl -s -m 5 -X POST "${GOTIFY_INTERNAL_URL}?token=${GOTIFY_APP_TOKEN}" \
+        -H "Content-Type: application/json" \
+        -d "{\"title\": \"${title}\", \"message\": \"${message}\", \"priority\": ${priority}}" >/dev/null 2>&1 || true
+}
+
+case "$EVENT_TYPE" in
+    ONBATT)
+        send_gotify "⚡ Grid Power Lost" "[$TIMESTAMP] Homelab is running on UPS battery (${UPS_NAME}). Staged shutdown countdown started." 8
+        logger -t nut-notify "Grid power failure detected - running on UPS battery."
+        ;;
+    ONLINE)
+        send_gotify "✅ Grid Power Restored" "[$TIMESTAMP] Utility AC power restored to ${UPS_NAME}. Battery recharging." 5
+        logger -t nut-notify "AC utility power restored."
+        ;;
+    LOWBATT)
+        send_gotify "🚨 UPS Battery Critical" "[$TIMESTAMP] Battery level critical on ${UPS_NAME}! Final Tier 4-6 shutdown initiated." 10
+        logger -t nut-notify "CRITICAL: UPS battery low. Enforcing emergency shutdown."
+        ;;
+    FSD)
+        send_gotify "🛑 Forced Shutdown Engaged" "[$TIMESTAMP] NUT Master has commanded immediate power cutoff across all clusters." 10
+        logger -t nut-notify "FSD signal received. Halting systems."
+        ;;
+    *)
+        logger -t nut-notify "Unhandled UPS event: ${EVENT_TYPE}"
+        ;;
+esac