feat: add async demo support and enhance template resolution

- Introduced async demo functionality in the README, allowing for asynchronous data preparation before rendering components.
- Updated WccDashboard, WccProperties, and WccSidebar to support Promise-based template factories.
- Implemented resolveTemplateFactory to handle both synchronous and asynchronous template results.
- Added tests for resolveTemplateFactory to ensure correct behavior for both sync and async templates.
- Updated pnpm workspace configuration.

ts_web/elements/wcc-sidebar.ts

@@ -1,13 +1,14 @@
 import * as plugins from '../wcctools.plugins.js';
 import { DeesElement, property, html, customElement, type TemplateResult } from '@design.estate/dees-element';
 import { WccDashboard } from './wcc-dashboard.js';
+import type { TTemplateFactory } from './wcctools.helpers.js';
 
 export type TElementType = 'element' | 'page';
 
 @customElement('wcc-sidebar')
 export class WccSidebar extends DeesElement {
   @property({ attribute: false })
-  public selectedItem: DeesElement | (() => TemplateResult);
+  public selectedItem: DeesElement | TTemplateFactory;
 
   @property({ attribute: false })
   public selectedType: TElementType;
@@ -202,7 +203,7 @@ export class WccSidebar extends DeesElement {
     `;
   }
 
-  public selectItem(typeArg: TElementType, itemNameArg: string, itemArg: (() => TemplateResult) | DeesElement) {
+  public selectItem(typeArg: TElementType, itemNameArg: string, itemArg: TTemplateFactory | DeesElement) {
     console.log('selected item');
     console.log(itemNameArg);
     console.log(itemArg);