feat(frontend): add Helm chart browser, monitoring, chart-references and values templates pages

Add new frontend pages for the multi-tenant OCDP platform:

- Charts page (/charts): Browse Harbor OCI registries to list Helm chart repositories
  and versions, with deploy modal to launch charts on selected clusters
- Monitoring page (/monitoring): Display cluster metrics (CPU/Memory/GPU usage)
  and per-node details with resource utilization bars
- Chart References page (/chart-references): CRUD for chart metadata references
- Values Templates page (/templates): CRUD for Helm values templates with version
  history and rollback support
- Sidebar: Add Charts navigation, update Storage and Templates links
- api.ts: Add all API client functions (clusterApi, registryApi, instanceApi,
  monitoringApi, storageApi, chartReferenceApi, valuesTemplateApi,
  workspaceApi, userApi) with full TypeScript types

Note: deploy flow and values template rollback not yet end-to-end tested.

backend/internal/domain/service/cluster_service.go

@@ -2,9 +2,16 @@ package service
 
 import (
 	"context"
+	"encoding/base64"
+	"fmt"
+	"os"
+
 	"github.com/google/uuid"
 	"github.com/ocdp/cluster-service/internal/domain/entity"
 	"github.com/ocdp/cluster-service/internal/domain/repository"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
 )
 
 // ClusterService 集群管理领域服务
@@ -75,3 +82,105 @@ func (s *ClusterService) ListClusters(ctx context.Context) ([]*entity.Cluster, e
 	return s.clusterRepo.List(ctx)
 }
 
+// ListByWorkspace 列出指定 workspace 的集群（包括共享集群）
+func (s *ClusterService) ListByWorkspace(ctx context.Context, workspaceID string) ([]*entity.Cluster, error) {
+	return s.clusterRepo.GetByWorkspace(ctx, workspaceID)
+}
+
+// GetSharedClusters 获取所有共享集群
+func (s *ClusterService) GetSharedClusters(ctx context.Context) ([]*entity.Cluster, error) {
+	return s.clusterRepo.GetShared(ctx)
+}
+
+// TestConnection 测试集群连接是否可用
+func (s *ClusterService) TestConnection(ctx context.Context, cluster *entity.Cluster) error {
+	// Mock 模式直接返回成功
+	if os.Getenv("ADAPTER_MODE") == "mock" {
+		return nil
+	}
+
+	// 尝试创建 k8s client
+	config, err := s.createRestConfig(cluster)
+	if err != nil {
+		return fmt.Errorf("failed to create k8s config: %w", err)
+	}
+
+	// 设置超时
+	config.Timeout = 30 * 1000000000 // 30秒 (nanoseconds)
+
+	clientset, err := kubernetes.NewForConfig(config)
+	if err != nil {
+		return fmt.Errorf("failed to create k8s client: %w", err)
+	}
+
+	// 测试连接 - 获取 version 信息
+	version, err := clientset.ServerVersion()
+	if err != nil {
+		return fmt.Errorf("failed to connect to cluster: %w", err)
+	}
+
+	if version == nil {
+		return fmt.Errorf("cluster returned nil version")
+	}
+
+	return nil
+}
+
+// createRestConfig 从 cluster 实体创建 k8s REST 配置
+func (s *ClusterService) createRestConfig(cluster *entity.Cluster) (*rest.Config, error) {
+	// 优先使用 kubeconfig 格式（如果 CAData 包含完整的 kubeconfig 内容）
+	if len(cluster.CAData) > 100 && (cluster.CAData[:11] == "apiVersion:" || cluster.CAData[:5] == "kind:") {
+		return clientcmd.RESTConfigFromKubeConfig([]byte(cluster.CAData))
+	}
+
+	// 使用证书或 token 认证
+	config := &rest.Config{
+		Host: cluster.Host,
+	}
+
+	if cluster.CertData != "" && cluster.KeyData != "" {
+		// 尝试解码 base64 编码的证书，如果失败则尝试原始 PEM
+		var caData, certData, keyData []byte
+		var decodeErr error
+
+		// 先尝试 base64 解码
+		caData, decodeErr = base64.StdEncoding.DecodeString(cluster.CAData)
+		if decodeErr != nil {
+			// base64 解码失败，可能是原始 PEM
+			caData = []byte(cluster.CAData)
+		}
+
+		certData, decodeErr = base64.StdEncoding.DecodeString(cluster.CertData)
+		if decodeErr != nil {
+			certData = []byte(cluster.CertData)
+		}
+
+		keyData, decodeErr = base64.StdEncoding.DecodeString(cluster.KeyData)
+		if decodeErr != nil {
+			keyData = []byte(cluster.KeyData)
+		}
+
+		config.TLSClientConfig = rest.TLSClientConfig{
+			CAData:   caData,
+			CertData: certData,
+			KeyData:  keyData,
+			Insecure: false,
+		}
+	} else if cluster.Token != "" {
+		config.BearerToken = cluster.Token
+	} else {
+		// 尝试使用本地 kubeconfig
+		kubeconfig := os.Getenv("KUBECONFIG")
+		if kubeconfig == "" {
+			kubeconfig = ".kube/config"
+		}
+		// 尝试从文件加载 kubeconfig
+		if _, err := os.Stat(kubeconfig); err == nil {
+			return clientcmd.BuildConfigFromFlags("", kubeconfig)
+		}
+		return clientcmd.BuildConfigFromFlags("", kubeconfig)
+	}
+
+	return config, nil
+}
+