feat(docker): group containers by compose/swarm + enrich widget (milestone 77 #942)

Container list now sub-groups each host's containers by compose project (or
swarm service) with a small subheading, preserving the running-first order;
hosts with no such labels render flat as before. The dashboard status widget
links each container to its detail page and surfaces enriched state inline —
health dot (healthy/unhealthy), restart count, and last non-zero exit code for
stopped containers. Completes the #942 UI surface.

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

plugins/docker/routes.py

@@ -175,6 +175,23 @@ async def rows():
             else:
                 g["stopped"] += 1
 
+    # Sub-group each host's containers by compose project (or swarm service),
+    # preserving the running-first ordering. Containers with neither label fall
+    # into an unlabelled bucket rendered flat, so plain hosts look unchanged.
+    for g in groups.values():
+        subs: dict[str, dict] = {}
+        order: list[str] = []
+        for item in g["containers"]:
+            c = item["container"]
+            label = c.compose_project or c.service_name or None
+            key = label or ""
+            if key not in subs:
+                subs[key] = {"label": label, "containers": []}
+                order.append(key)
+            subs[key]["containers"].append(item)
+        g["subgroups"] = [subs[k] for k in order]
+        g["grouped"] = any(s["label"] for s in g["subgroups"])
+
     host_groups = sorted(groups.values(), key=lambda g: g["host_name"].lower())
     running = sum(g["running"] for g in host_groups)
     total = len(containers)