feat(docker): per-container enrichment — health, restarts, exit code, I/O, grouping

First slice of milestone 77 (Docker monitoring depth). Surfaces real per-container
stats beyond basic state, all read-only on the existing push model.

- agent (→1.4.0): collect_docker now inspects each container (health, restart
  count, exit code, OOM) and reads net + block I/O from the stats payload; pulls
  compose project + swarm service/task/node from container labels. Per-container
  inspect+stats calls run over a small bounded ThreadPool so the ~1s-per-stats
  blocking doesn't stretch the sample on a busy host.
- schema (docker_003): additive columns on docker_containers — health, exit_code,
  oom_killed, compose_project, service_name, task_id, node_id, and BigInteger
  net/blk byte counters.
- ingest: persists the enrichment + restart_count (.get keeps older agents working).
- ui: Docker page rows now show health badge, uptime ("up 3d 4h"), restart count,
  exit code (+OOM) for stopped containers, and compose/service grouping label.
- tests: agent helpers (grouping, inspect fields, net/IO sum) + collect_docker
  assembly incl. inspect; integration asserts enrichment round-trips.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016Jg27rgypiW2efULXJDtMC

plugins/docker/routes.py

@@ -1,6 +1,8 @@
 # plugins/docker/routes.py
 from __future__ import annotations
 import json
+from datetime import datetime, timezone
+
 from quart import Blueprint, current_app, render_template, request
 from sqlalchemy import select
 
@@ -13,6 +15,25 @@ from .models import DockerContainer, DockerMetric
 docker_bp = Blueprint("docker", __name__, template_folder="templates")
 
 
+def _human_uptime(started_at: datetime | None) -> str | None:
+    """Compact 'how long running' string (e.g. '3d 4h', '5h 12m', '8m')."""
+    if started_at is None:
+        return None
+    if started_at.tzinfo is None:
+        started_at = started_at.replace(tzinfo=timezone.utc)
+    secs = int((datetime.now(timezone.utc) - started_at).total_seconds())
+    if secs < 0:
+        return None
+    d, rem = divmod(secs, 86400)
+    h, rem = divmod(rem, 3600)
+    m, _ = divmod(rem, 60)
+    if d:
+        return f"{d}d {h}h"
+    if h:
+        return f"{h}h {m}m"
+    return f"{m}m"
+
+
 def _sparkline(values: list[float], width: int = 80, height: int = 20) -> str:
     if len(values) < 2:
         return f'<svg width="{width}" height="{height}"></svg>'
@@ -119,6 +140,7 @@ async def rows():
             g["containers"].append({
                 "container": c,
                 "ports": json.loads(c.ports_json) if c.ports_json else [],
+                "uptime": _human_uptime(c.started_at) if c.status == "running" else None,
                 "sparkline_cpu": _sparkline(cpu_hist),
                 "sparkline_mem": _sparkline(mem_hist),
             })