fix(player): render literal x instead of HTML entity for dismiss button

htm/Preact template literals insert text as a DOM text node rather than
parsing it as HTML, so the × entity was never decoded and showed
up literally in the player UI's announcement banner. The admin UI's
equivalent button is unaffected because it's built as an HTML string
inserted via innerHTML, where the browser does decode entities.

Fixes the player-UI regression noted in #591.

pkg/service/soundtouchweb/static/js/components/Announcements.js

@@ -39,7 +39,7 @@ export function Announcements() {
                         ${a.message}
                         ${a.link_url ? html` <a href=${a.link_url} target="_blank" rel="noopener">${a.link_text || a.link_url}</a>` : null}
                     </span>
-                    <button class="announcement-dismiss" onClick=${() => dismiss(a.id)} title="Dismiss">&times;</button>
+                    <button class="announcement-dismiss" onClick=${() => dismiss(a.id)} title="Dismiss">×</button>
                 </div>
             `)}
         </div>