fix(kiosk): force STREAM_MUSIC for TTS + JS feedback callbacks

Android TTS was silently failing because engine.speak() used the default
audio stream, which may be muted while the media stream is not.

Changes:
- KioskActivity: speak() now passes Bundle with KEY_PARAM_STREAM=STREAM_MUSIC
  so TTS plays on the same channel as beep/media audio
- KioskActivity: add UtteranceProgressListener that calls window._kioskTtsDone()
  or window._kioskTtsError(uid, code) back into the WebView on completion/failure
- app.js testTTS(): kiosk path now shows real result from Android callbacks
  (success/error) with a 4s fallback timeout showing actionable troubleshooting hints

assets/js/app.js

@@ -14180,8 +14180,26 @@ async function testTTS() {
             s.tts_rate  = parseFloat(document.getElementById('setting-tts-rate')?.value)  || 1;
             s.tts_pitch = parseFloat(document.getElementById('setting-tts-pitch')?.value) || 1;
             saveSettingsToStorage(s);
+            if (statusEl) { statusEl.style.display = 'block'; statusEl.className = 'settings-status'; statusEl.textContent = '⏳ Invio al motore TTS Android...'; }
+            // Register callbacks: Android will call these after speak completes/fails
+            let _ttsTestTimer = null;
+            window._kioskTtsDone = (uid) => {
+                clearTimeout(_ttsTestTimer);
+                window._kioskTtsDone = null; window._kioskTtsError = null;
+                if (statusEl) { statusEl.className = 'settings-status success'; statusEl.textContent = '✅ Voce riprodotta correttamente.'; }
+            };
+            window._kioskTtsError = (uid, code) => {
+                clearTimeout(_ttsTestTimer);
+                window._kioskTtsDone = null; window._kioskTtsError = null;
+                const msg = code == -1 ? 'sintesi non riuscita' : code == -2 ? 'lingua non supportata' : code == -3 ? 'servizio non disponibile' : ('codice ' + code);
+                if (statusEl) { statusEl.className = 'settings-status error'; statusEl.textContent = '❌ Errore TTS Android (' + msg + ') — installa o aggiorna Google Text-to-Speech dal Play Store.'; }
+            };
+            // Timeout: if Android doesn't callback within 4s, warn about media volume
+            _ttsTestTimer = setTimeout(() => {
+                window._kioskTtsDone = null; window._kioskTtsError = null;
+                if (statusEl) { statusEl.className = 'settings-status error'; statusEl.textContent = '⚠️ Nessun feedback ricevuto. Controlla: 1) volume media del dispositivo non sia 0; 2) Google Text-to-Speech installato e aggiornato; 3) pacchetto vocale italiano scaricato.'; }
+            }, 4000);
             _speakBrowser('Test vocale EverShelf. La sintesi vocale funziona correttamente.');
-            if (statusEl) { statusEl.style.display = 'block'; statusEl.className = 'settings-status success'; statusEl.textContent = '✅ Riproduzione in corso — controlla l\'audio del dispositivo.'; }
             return;
         }
         if (!window.speechSynthesis) {

evershelf-kiosk/app/src/main/kotlin/it/dadaloop/evershelf/kiosk/KioskActivity.kt

@@ -18,7 +18,9 @@ import android.os.Bundle
 import android.os.Handler
 import android.os.Looper
 import android.provider.Settings
+import android.media.AudioManager
 import android.speech.tts.TextToSpeech
+import android.speech.tts.UtteranceProgressListener
 import android.view.View
 import android.view.WindowInsets
 import android.view.WindowInsetsController
@@ -144,6 +146,25 @@ class KioskActivity : AppCompatActivity() {
                 if (res == TextToSpeech.LANG_MISSING_DATA || res == TextToSpeech.LANG_NOT_SUPPORTED) {
                     tts?.language = Locale.getDefault()
                 }
+                tts?.setOnUtteranceProgressListener(object : UtteranceProgressListener() {
+                    override fun onStart(utteranceId: String?) {}
+                    override fun onDone(utteranceId: String?) {
+                        runOnUiThread {
+                            webView.evaluateJavascript("if(window._kioskTtsDone)window._kioskTtsDone('$utteranceId')", null)
+                        }
+                    }
+                    @Deprecated("Deprecated in API 21")
+                    override fun onError(utteranceId: String?) {
+                        runOnUiThread {
+                            webView.evaluateJavascript("if(window._kioskTtsError)window._kioskTtsError('$utteranceId','error')", null)
+                        }
+                    }
+                    override fun onError(utteranceId: String?, errorCode: Int) {
+                        runOnUiThread {
+                            webView.evaluateJavascript("if(window._kioskTtsError)window._kioskTtsError('$utteranceId',$errorCode)", null)
+                        }
+                    }
+                })
                 ttsReady = true
             }
         }
@@ -466,7 +487,10 @@ class KioskActivity : AppCompatActivity() {
                 if (!ttsReady) return
                 engine.setSpeechRate(rate.coerceIn(0.1f, 4f))
                 engine.setPitch(pitch.coerceIn(0.1f, 4f))
-                engine.speak(text, android.speech.tts.TextToSpeech.QUEUE_FLUSH, null, "kiosk_tts")
+                val params = Bundle().apply {
+                    putInt(TextToSpeech.Engine.KEY_PARAM_STREAM, AudioManager.STREAM_MUSIC)
+                }
+                engine.speak(text, TextToSpeech.QUEUE_FLUSH, params, "kiosk_tts")
             }
             @JavascriptInterface
             fun stopSpeech() { tts?.stop() }