Fleet monitoring: sysstat 28d + perfsnap/PSI/iotop timers + on-demand toolbox container (#826)

- monitoring/node-install.sh: idempotent per-node installer (sar HISTORY=28,
  three oneshot timers, per-node conf with qemu.slice/lxc cgroup globs)
- monitoring/collectors + systemd units: iotop-snap 15min, perfsnap 60s,
  psi-textfile 15s (now sources /etc/knelperf/perfsnap.conf; multi-glob)
- monitoring/toolbox: pct LXC (vmid 950, privileged, apparmor unconfined,
  stopped at rest) + knelperf-toolbox wrapper + Dockerfile variant
- monitoring/deploy-fleet.sh: workstation-side rollout driver
- piloted on pfv-tsys1: per-VM PSI gauges verified live

Redmine: https://projects.knownelement.com/issues/826

monitoring/toolbox/toolbox-pkgs.txt

@@ -0,0 +1,37 @@
+# knelperf-toolbox package manifest — shared by the LXC bootstrap and the
+# Docker image variant. One package (or apt argument) per line; # = comment.
+# Docs: https://community.turnsys.com/t/328
+bpftrace
+bcc-tools
+sysstat
+iotop
+sysbench
+fio
+iperf3
+stress-ng
+linux-perf
+jq
+bc
+curl
+procps
+psmisc
+util-linux
+pciutils
+usbutils
+ethtool
+net-tools
+bind9-dnsutils
+smartmontools
+nvme-cli
+hdparm
+lm-sensors
+numactl
+hwloc-nox
+strace
+ltrace
+file
+rsync
+openssh-client
+vim-tiny
+less
+tmux