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-icon/dees-icon.ts

@@ -9,6 +9,7 @@ import {
 } from '@design.estate/dees-element';
 
 import * as domtools from '@design.estate/dees-domtools';
+import { themeDefaultStyles } from '../00theme.js';
 
 import { icon, type IconDefinition } from '@fortawesome/fontawesome-svg-core';
 import {
@@ -325,8 +326,10 @@ export class DeesIcon extends DeesElement {
   }
 
   public static styles = [
+    themeDefaultStyles,
     cssManager.defaultStyles,
     css`
+      /* TODO: Migrate hardcoded values to --dees-* CSS variables */
       :host {
         display: inline-flex;
         align-items: center;
@@ -334,7 +337,7 @@ export class DeesIcon extends DeesElement {
         line-height: 1;
         vertical-align: middle;
       }
-      
+
       /* Improve rendering performance */
       #iconContainer svg {
         display: block;