refactor: full-stack restructure with multi-tenancy, workspace management, and K8s diagnostics

- Add Workspace domain (entity, repository, service, handler, DTO)
- Add multi-tenant K8s client with tenant binding and quota management
- Add K8s diagnostics client (instance diagnostics)
- Add authorization middleware (authz package)
- Restructure frontend to feature-based architecture (features/)
- Add User Management page in configuration
- Add AccessDenied page and route guards
- Refactor shared components (form inputs, layout, UI)
- Update Tailwind config for new design system
- Add comprehensive documentation (docs/, tasks/, plans)
- Improve cluster service with better kubeconfig handling
- Add tests for crypto, config, helm client, tenant binding

backend/internal/domain/repository/metrics_client.go

@@ -10,8 +10,7 @@ import (
 type MetricsClient interface {
 	// GetClusterMetrics 获取集群的监控指标
 	GetClusterMetrics(ctx context.Context, clusterID string) (*entity.ClusterMetrics, error)
-	
+
 	// GetNodeMetrics 获取集群的节点指标
 	GetNodeMetrics(ctx context.Context, clusterID string) ([]*entity.NodeMetrics, error)
 }
-