feat: share proxmox cluster client with worker

worker/internal/tasks/proxmox_poll.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"log/slog"
 	"time"
@@ -13,6 +14,8 @@ import (
 
 const TypeProxmoxTaskPoll = "proxmox.task.poll"
 
+var ErrClusterNotFound = errors.New("cluster not found")
+
 type ProxmoxTaskPollPayload struct {
 	ClusterID     string `json:"cluster_id"`
 	Node          string `json:"node"`