feat(theme,interfaces): Introduce a global theming system and unify menu/tab interfaces; migrate components to use themeDefaultStyles and update APIs accordingly

ts_web/elements/dees-label/dees-label.ts

@@ -13,6 +13,7 @@ import {
 } from '@design.estate/dees-element';
 
 import { demoFunc } from './dees-label.demo.js';
+import { themeDefaultStyles } from '../00theme.js';
 
 @customElement('dees-label')
 export class DeesLabel extends DeesElement {
@@ -39,8 +40,10 @@ export class DeesLabel extends DeesElement {
   accessor required: boolean = false;
 
   public static styles = [
+    themeDefaultStyles,
     cssManager.defaultStyles,
     css`
+      /* TODO: Migrate hardcoded values to --dees-* CSS variables */
       :host {
         font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
       }