fix(admin): blur visibility toggle after click to dismiss tooltip

After toggling announcement visibility, the button retains browser
focus, which keeps the tooltip visible even after the cursor moves
away. Call blur() to release focus and allow the tooltip to dismiss
naturally on mouse-out.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: huoxin233

framework/core/js/src/admin/components/AnnouncementWidget.tsx

@@ -84,7 +84,14 @@ export default class AnnouncementsWidget extends DashboardWidget {
               </Tooltip>
             )}
             <Tooltip text={app.translator.trans(this.hidden ? 'core.admin.announcements.show' : 'core.admin.announcements.hide')}>
-              <Button className="Button Button--icon" icon={this.hidden ? 'fas fa-eye' : 'fas fa-eye-slash'} onclick={() => this.toggleHidden()} />
+              <Button
+                className="Button Button--icon"
+                icon={this.hidden ? 'fas fa-eye' : 'fas fa-eye-slash'}
+                onclick={(e: any) => {
+                  this.toggleHidden();
+                  e.currentTarget.blur();
+                }}
+              />
             </Tooltip>
           </div>
         </div>