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/adapter/output/persistence/postgres/instance_repository.go

@@ -431,3 +431,105 @@ func (r *InstanceRepository) List(ctx context.Context) ([]*entity.Instance, erro
 
 	return instances, nil
 }
+
+// GetByWorkspace 列出指定工作空间的所有实例（用于配额检查）
+func (r *InstanceRepository) GetByWorkspace(ctx context.Context, workspaceID string) ([]*entity.Instance, error) {
+	query := `
+		SELECT id, cluster_id, workspace_id, owner_id, name, namespace, registry_id, repository, chart, version,
+		       description, values, values_yaml, values_template_id, user_override_yaml,
+		       status, status_reason, last_operation, last_error, revision,
+		       cpu_requested, memory_requested, gpu_requested, gpu_memory_requested,
+		       created_at, updated_at
+		FROM instances
+		WHERE workspace_id = $1
+		ORDER BY created_at DESC
+	`
+
+	rows, err := r.db.conn.QueryContext(ctx, query, workspaceID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get instances by workspace: %w", err)
+	}
+	defer rows.Close()
+
+	instances := make([]*entity.Instance, 0)
+	for rows.Next() {
+		instance := &entity.Instance{}
+		var (
+			valuesJSON          []byte
+			statusReason        sql.NullString
+			lastOperation       sql.NullString
+			lastError           sql.NullString
+			valuesTemplateID    sql.NullString
+			userOverrideYAML    sql.NullString
+			memoryRequested     sql.NullString
+			gpuMemoryRequested  sql.NullString
+		)
+
+		err := rows.Scan(
+			&instance.ID,
+			&instance.ClusterID,
+			&instance.WorkspaceID,
+			&instance.OwnerID,
+			&instance.Name,
+			&instance.Namespace,
+			&instance.RegistryID,
+			&instance.Repository,
+			&instance.Chart,
+			&instance.Version,
+			&instance.Description,
+			&valuesJSON,
+			&instance.ValuesYAML,
+			&valuesTemplateID,
+			&userOverrideYAML,
+			&instance.Status,
+			&statusReason,
+			&lastOperation,
+			&lastError,
+			&instance.Revision,
+			&instance.CPURequested,
+			&memoryRequested,
+			&instance.GPURequested,
+			&gpuMemoryRequested,
+			&instance.CreatedAt,
+			&instance.UpdatedAt,
+		)
+		if err != nil {
+			return nil, fmt.Errorf("failed to scan instance: %w", err)
+		}
+
+		if valuesJSON != nil {
+			if err := json.Unmarshal(valuesJSON, &instance.Values); err != nil {
+				return nil, fmt.Errorf("failed to unmarshal values: %w", err)
+			}
+		}
+		if valuesTemplateID.Valid {
+			instance.ValuesTemplateID = valuesTemplateID.String
+		}
+		if userOverrideYAML.Valid {
+			instance.UserOverrideYAML = userOverrideYAML.String
+		}
+		if statusReason.Valid {
+			instance.StatusReason = statusReason.String
+		}
+		if lastOperation.Valid {
+			instance.LastOperation = entity.InstanceOperation(lastOperation.String)
+		}
+		if lastError.Valid {
+			instance.LastError = lastError.String
+		}
+		if memoryRequested.Valid {
+			instance.MemoryRequested = memoryRequested.String
+		}
+		if gpuMemoryRequested.Valid {
+			instance.GPUMemoryRequested = gpuMemoryRequested.String
+		}
+
+		instances = append(instances, instance)
+	}
+
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("rows iteration error: %w", err)
+	}
+
+	return instances, nil
+}