fix: ProxmoxCollector read wrong shape for node mem/disk

/nodes/{node}/status nests memory/rootfs objects; the LXC listing
endpoint uses flat mem/maxmem/disk/maxdisk. Code assumed the LXC
shape for both, so the Proxmox host's own memPct/diskPct were NaN ->
serialized as null the whole time. Found while checking sparkline
history data looked wrong for the host card specifically.

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

apps/api/src/collectors/proxmox.ts

@@ -15,10 +15,11 @@ interface ProxmoxConfig {
 
 interface ProxmoxNodeStatus {
   cpu: number;
-  mem: number;
-  maxmem: number;
-  disk: number;
-  maxdisk: number;
+  // Unlike the LXC listing endpoint, /nodes/{node}/status nests these instead
+  // of using flat mem/maxmem/disk/maxdisk — mixing the two shapes up silently
+  // produced NaN (serialized as null over JSON) instead of throwing.
+  memory: { total: number; used: number };
+  rootfs: { total: number; used: number };
   uptime: number;
 }
 
@@ -73,12 +74,12 @@ export class ProxmoxCollector implements Collector {
       group: "Proxmox Host",
       status: "up",
       cpuPct: round(nodeStatus.cpu * 100),
-      memPct: round((nodeStatus.mem / nodeStatus.maxmem) * 100),
-      diskPct: round((nodeStatus.disk / nodeStatus.maxdisk) * 100),
+      memPct: round((nodeStatus.memory.used / nodeStatus.memory.total) * 100),
+      diskPct: round((nodeStatus.rootfs.used / nodeStatus.rootfs.total) * 100),
       memPressurePct: null,
       cpuPressurePct: null,
       uptimeSec: nodeStatus.uptime,
-      meta: { maxmem: nodeStatus.maxmem, maxdisk: nodeStatus.maxdisk },
+      meta: { maxmem: nodeStatus.memory.total, maxdisk: nodeStatus.rootfs.total },
     });
 
     for (const ct of lxcs) {