Add host stats to the Proxmox page

The Proxmox page only showed guest (VM/LXC) status; there was no view
of the underlying host(s) themselves -- uptime, CPU/RAM usage, or how
full each storage pool is.

New adapter.listNodeStats() calls GET /nodes/{node}/status and GET
/nodes/{node}/storage for every online node (a node going down
shouldn't blank the whole page, same tolerance as listGuests()) and
returns uptime, CPU usage % + core count + load average, RAM/swap
usage, and per-storage (local, LVM-thin, ZFS, NFS, ...) used/total.
New GET /:id/proxmox/nodes route alongside the existing /guests one.

One card per online node now sits above the VM/LXC table, showing
these stats plus a small storage table with usage bars (reusing the
same green/yellow/red thresholds as the Servers detail page and the
Synology page). Handles a multi-node cluster by rendering one card
per node, and storages with no active/total data (e.g. an offline NFS
mount) render as an "Inactive" badge with blank usage instead of
throwing.

Verified end-to-end against a local mock Proxmox API server over real
TLS (a throwaway self-signed cert, matching how the adapter's
`insecure` option is meant to be used) since this sandbox can't reach
the user's actual Proxmox cluster -- confirmed CPU fraction-to-percent
conversion, load average parsing, byte fields, and that a
null-valued/inactive storage doesn't break parsing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

server/src/routes/integrations.ts

@@ -628,6 +628,18 @@ integrationsRouter.get("/:id/proxmox/guests", asyncHandler(async (req, res) => {
   }
 }));
 
+integrationsRouter.get("/:id/proxmox/nodes", asyncHandler(async (req, res) => {
+  const found = await requireProxmoxAdapter(req, res);
+  if (!found) return;
+
+  try {
+    const nodes = await found.adapter.listNodeStats();
+    res.json({ nodes });
+  } catch (err) {
+    res.status(502).json({ error: err instanceof Error ? err.message : String(err) });
+  }
+}));
+
 const proxmoxActions = ["start", "stop", "restart", "shutdown"] as const;
 
 for (const action of proxmoxActions) {