feat(hosts): a host's page stays short — Docker folds past the busiest, monitors add on their own form, agent actions under Manage (#5276, #5277, #5278)

Docker panel (#5276): problems first, then the 8 busiest running
containers by CPU; the other running and the stopped fold behind one
"+N more running · M stopped" line. Containers that are not swarm tasks
read the way the Docker page reads them: CI jobs as "CI: workflow · job",
buildx builders as "BuildKit builder · name".

Monitors card (#5277): the edit/delete icon buttons and the inline add
form are gone. Each row links to its monitor's page; "Add monitor" opens
the add form filed under this host, starting from its address, with the
host in its breadcrumbs and Cancel back to it.

Agent card (#5278): Full metrics stays in view; Update, Rotate token,
Unregister agent (was "Remove") and Re-provision sit under "Manage agent".

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

steward/monitors/routes.py

@@ -88,11 +88,21 @@ async def add_monitor():
 
 
 async def _new_form(form, mtype: str, error: str | None = None) -> str:
-    """The add form, holding what was typed when `error` sends it back."""
+    """The add form, holding what was typed when `error` sends it back. Opened
+    from a host's page (host_id), it files the monitor under that host and
+    starts from the host's address."""
     values = {k: form.get(k, "") for k in ("name", "target", "host_id")}
     values["check_interval_seconds"] = form.get("check_interval_seconds", 0)
+    host = None
+    if values["host_id"]:
+        async with current_app.db_sessionmaker() as db:
+            host = await db.get(Host, values["host_id"])
+        if host is None:
+            values["host_id"] = ""
+        elif not values["target"]:
+            values["target"] = host.address or host.name
     return await render_template(
-        "monitors/form.html", monitor=None, values=values,
+        "monitors/form.html", monitor=None, values=values, host=host,
         mtype=mtype if mtype in MONITOR_TYPE_VALUES else MonitorType.icmp.value,
         config=_form_opts(form, mtype) if error and mtype in MONITOR_TYPE_VALUES else {},
         types=list(MonitorType), error=error,