refactor: downgrade Angular CLI version and remove unused branding properties

- Downgraded @angular/cli from 21.2.2 to 19.2.22 in package.json.
- Removed the brand$ observable from BrandingService as it was not utilized.
- Eliminated the setting of the --brand-hero-image CSS variable and related styles in styles.scss.

Author: heyding

.github/workflows/gh-pages.yml

@@ -3,7 +3,7 @@ name: Deploy to GitHub Pages
 on:
   push:
     branches:
-      - main
+      - master
   workflow_dispatch:
 
 permissions: