Style audio device select, hide mini player volume on tablet

- Native select with explicit font stack and focus glow
- Hide mini player volume section below 900px

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

media_server/static/js/app.js

@@ -477,7 +477,6 @@
             try {
                 const token = localStorage.getItem('media_server_token');
 
-                // Fetch devices and current status in parallel
                 const [devicesResp, statusResp] = await Promise.all([
                     fetch('/api/media/visualizer/devices', {
                         headers: { 'Authorization': `Bearer ${token}` }
@@ -497,7 +496,6 @@
                     return;
                 }
 
-                // Show section
                 section.style.display = '';
 
                 // Populate dropdown (keep auto-detect as first option)
@@ -519,10 +517,8 @@
                     }
                 }
 
-                // Update status indicator
                 updateAudioDeviceStatus(status);
             } catch (e) {
-                // Silently hide if unavailable
                 section.style.display = 'none';
             }
         }
@@ -562,7 +558,6 @@
                 if (resp.ok) {
                     const result = await resp.json();
                     updateAudioDeviceStatus(result);
-                    // Re-check visualizer availability since device changed
                     await checkVisualizerAvailability();
                     if (visualizerEnabled) applyVisualizerMode();
                     showToast(t('settings.audio.device_changed'), 'success');