feat(docker): uptime from StartedAt, a restart is an event, host totals count physical devices only (#5153)

- Agent: started_at comes from inspect's State.StartedAt (nanoseconds
  trimmed; Docker's zero time is "never started"), not the list's Created,
  so a restarted container's uptime counts from its restart.
- A rising restart_count between two snapshots emits a "restart" event
  ("restart #3", or "3 restarts, now #5"), said instead of a start; a
  restart then a death gives both. A count that falls (recreated under the
  same name) says nothing. The timeline draws it as ↻.
- Network and disk I/O count what the kernel calls physical: interfaces
  not under /sys/devices/virtual/net (bridges, docker0, veth, vxlan, tun),
  block devices with a device behind them (not dm, md, zram), so a byte is
  not counted twice. Where /sys calls everything virtual (an agent in LXC)
  the name-filtered set is kept rather than reporting no traffic.
- Agent tests updated for #5152's (status, detail, containers) and
  (is_manager, topology) shapes; the no-Docker disk test now states the
  case it was passing for by accident.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugins/docker/mcp_tools.py

@@ -308,7 +308,7 @@ async def get_container(container: str, host: str = "", range: str = "24h", even
     range: the window for `cpu_pct_history` and `mem_pct_history` (min, avg,
       max, p95, last and a ≤60-point series) — "1h", "6h", "24h" (default),
       "7d" or "30d". `cpu_pct` and `mem_pct` are the latest reported values.
-    events: how many lifecycle events (start, stop, die, oom, health_change)
+    events: how many lifecycle events (start, restart, stop, die, oom, health_change)
       to return, newest first (default 20, max 100).
 
     A container Docker has since removed (a dead Swarm task, a `docker rm`)