feat(proxmox): add LXC container stats endpoint with streaming support

Implement a new API endpoint to retrieve real-time statistics for Proxmox
LXC containers, similar to `docker stats` functionality.

Changes:
- Add `GET /api/v1/proxmox/stats/:node/:vmid` endpoint with HTTP and WebSocket support
- Implement resource polling loop to cache VM metadata every 3 seconds
- Create `LXCStats()` method with streaming (websocket) and single-shot modes
- Format output as: STATUS|CPU%|MEM USAGE/LIMIT|MEM%|NET I/O|BLOCK I/O
- Add `GetResource()` method for efficient VM resource lookup by kind and ID
- Fix task creation bug using correct client reference

Example response:
  running|31.1%|9.6GiB/20GiB|48.87%|4.7GiB/3.3GiB|25GiB/36GiB

internal/proxmox/client.go

@@ -2,20 +2,35 @@ package proxmox
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"strconv"
+	"sync"
 
 	"github.com/bytedance/sonic"
 	"github.com/luthermonson/go-proxmox"
+	"github.com/rs/zerolog/log"
 )
 
 type Client struct {
 	*proxmox.Client
-	proxmox.Cluster
+	*proxmox.Cluster
 	Version *proxmox.Version
+	// id -> resource; id: lxc/<vmid> or qemu/<vmid>
+	resources   map[string]*proxmox.ClusterResource
+	resourcesMu sync.RWMutex
 }
 
+var (
+	ErrResourceNotFound = errors.New("resource not found")
+	ErrNoResources      = errors.New("no resources")
+)
+
 func NewClient(baseUrl string, opts ...proxmox.Option) *Client {
-	return &Client{Client: proxmox.NewClient(baseUrl, opts...)}
+	return &Client{
+		Client:    proxmox.NewClient(baseUrl, opts...),
+		resources: make(map[string]*proxmox.ClusterResource),
+	}
 }
 
 func (c *Client) UpdateClusterInfo(ctx context.Context) (err error) {
@@ -24,15 +39,49 @@ func (c *Client) UpdateClusterInfo(ctx context.Context) (err error) {
 		return err
 	}
 	// requires (/, Sys.Audit)
-	if err := c.Get(ctx, "/cluster/status", &c.Cluster); err != nil {
+	cluster, err := c.Client.Cluster(ctx)
+	if err != nil {
 		return err
 	}
+	c.Cluster = cluster
+
 	for _, node := range c.Cluster.Nodes {
-		Nodes.Add(&Node{name: node.Name, id: node.ID, client: c.Client})
+		Nodes.Add(NewNode(c, node.Name, node.ID))
+	}
+	if cluster.Name == "" && len(c.Cluster.Nodes) == 1 {
+		cluster.Name = c.Cluster.Nodes[0].Name
 	}
 	return nil
 }
 
+func (c *Client) UpdateResources(ctx context.Context) error {
+	c.resourcesMu.Lock()
+	defer c.resourcesMu.Unlock()
+	resourcesSlice, err := c.Cluster.Resources(ctx, "vm")
+	if err != nil {
+		return err
+	}
+	clear(c.resources)
+	for _, resource := range resourcesSlice {
+		c.resources[resource.ID] = resource
+	}
+	log.Debug().Str("cluster", c.Cluster.Name).Msgf("[proxmox] updated %d resources", len(c.resources))
+	return nil
+}
+
+// GetResource gets a resource by kind and id.
+// kind: lxc or qemu
+// id: <vmid>
+func (c *Client) GetResource(kind string, id int) (*proxmox.ClusterResource, error) {
+	c.resourcesMu.RLock()
+	defer c.resourcesMu.RUnlock()
+	resource, ok := c.resources[kind+"/"+strconv.Itoa(id)]
+	if !ok {
+		return nil, ErrResourceNotFound
+	}
+	return resource, nil
+}
+
 // Key implements pool.Object
 func (c *Client) Key() string {
 	return c.Cluster.ID