feat: power-loss boot resilience for Klubhaus DietPi

- restart: always for stack services
- harden-boot.sh: fsck.repair, panic reboot, hardware watchdog,
  docker+zerotier enabled, klubhaus-stack.service autostart
- kuma-online.sh: push up-heartbeat to Kuma on boot
- RESILIENCE.md documents the Aug 30 failure + apply steps

scripts/kuma-online.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Push an "up" heartbeat to every configured Kuma push URL.
+# URLs live in /root/.kuma-push.env (one per line, # for comments).
+ENV_FILE=/root/.kuma-push.env
+
+[ -f "$ENV_FILE" ] || { echo "no $ENV_FILE"; exit 0; }
+
+while IFS= read -r url; do
+    case "$url" in
+        ""|"#"*) continue ;;
+    esac
+    if curl -fsS -G --data-urlencode "status=up" --data-urlencode "msg=pi-online" "$url" >/dev/null 2>&1; then
+        echo "OK  ${url#https://up.notsosm.art/api/push/}"
+    else
+        echo "FAIL ${url#https://up.notsosm.art/api/push/}"
+    fi
+done < "$ENV_FILE"