Dashboard Studio 2.2.1: sports match centre, Import JSON back, no double entities

- Sports card: crests in team colours, position and record, countdown,
  win-probability bar, live clock and last play, venue
- Import JSON back in the builder's menu
- Fixed: picking an entity with the keyboard added it twice; existing
  duplicates are removed when dashboards load

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dashboard_studio/web/index.html

@@ -53,6 +53,7 @@
         <button role="menuitem" data-menu="undo-history" data-icon="undo" data-i18n>Undo history…</button>
         <button role="menuitem" data-menu="share" data-icon="share" data-i18n>Share…</button>
         <button role="menuitem" data-menu="export" data-icon="exit" data-i18n>Export as JSON</button>
+        <button role="menuitem" data-menu="import" data-icon="plus" data-i18n>Import JSON…</button>
       </div>
     </header>