Replace Bluetooth with Focus mode in iOS audio tips

Focus mode is more likely to cause unexpected audio silencing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

play.html

@@ -362,7 +362,7 @@
 
         <!-- iOS Audio Unlock -->
         <div id="iosAudioBanner" class="ios-audio-banner">
-          <p>Check: not on silent, volume up, no Bluetooth audio. Then tap:</p>
+          <p>Check: not on silent, volume up, Focus mode off. Then tap:</p>
           <button id="enableAudioBtn" type="button">Enable Audio</button>
         </div>