fix: TTS test ask user if heard + PHP 8 end() ref bug + DB migration guard for fresh volumes

- app.js: TTS kiosk timeout 4s → 10s; fires interactive 'Hai sentito?' YES/NO
  prompt instead of showing error (TTS can take 6-8s; UtteranceProgressListener
  may not fire on all firmware); YES → success, NO → troubleshooting steps
- translations: add heard_question/heard_yes/heard_no/test_ok_kiosk/test_fail_steps
  to all 5 languages (it/en/de/fr/es) under settings.tts
- api/index.php: fix end() PHP 8.0+ reference error in _offFetchProduct()
  (categories_hierarchy stored in temp var before calling end())  (fixes #130)
- api/database.php: migrateDB() now checks sqlite_master for 'products' table;
  if missing, calls initializeDB() and returns — no ALTER on nonexistent table
  (fixes #133, covers #131)
- api/index.php: health_check db_row_count query guarded against missing
  inventory table (fixes #131)

translations/de.json

@@ -701,7 +701,12 @@
             "voices_hint": "Verfügbare Stimmen hängen vom Betriebssystem und Browser ab. Auf macOS/iOS ist die Stimme Paola (Italienisch) verfügbar. Drücken Sie ↺ wenn die Liste nicht lädt.",
             "url_missing": "⚠️ Endpunkt-URL fehlt.",
             "test_sending": "⏳ Wird gesendet…",
-            "test_ok": "✅ Antwort {code} — prüfe ob der Lautsprecher gesprochen hat."
+            "test_ok": "✅ Antwort {code} — prüfe ob der Lautsprecher gesprochen hat.",
+            "heard_question": "Hast du die Stimme gehört?",
+            "heard_yes": "Ja, ich habe es gehört",
+            "heard_no": "Nein, ich habe nichts gehört",
+            "test_ok_kiosk": "TTS funktioniert.",
+            "test_fail_steps": "Prüfe: 1) Medienvolume ist nicht 0; 2) Google Text-to-Speech installiert und aktualisiert; 3) Deutsches Sprachpaket in den Android TTS-Einstellungen heruntergeladen."
         },
         "language": {
             "title": "🌐 Sprache",

translations/en.json

@@ -701,7 +701,12 @@
             "voices_hint": "Available voices depend on the OS and browser. On macOS/iOS the Paola (Italian) voice is available. Press ↺ if the list does not load.",
             "url_missing": "⚠️ Endpoint URL missing.",
             "test_sending": "⏳ Sending…",
-            "test_ok": "✅ Response {code} — check that the speaker has spoken."
+            "test_ok": "✅ Response {code} — check that the speaker has spoken.",
+            "heard_question": "Did you hear the voice?",
+            "heard_yes": "Yes, I heard it",
+            "heard_no": "No, I didn't hear it",
+            "test_ok_kiosk": "TTS is working.",
+            "test_fail_steps": "Check: 1) media volume is not 0; 2) Google Text-to-Speech is installed and updated; 3) Italian voice package is downloaded in Android TTS settings."
         },
         "language": {
             "title": "🌐 Language",

translations/es.json

@@ -694,7 +694,12 @@
             "voices_hint": "Las voces disponibles dependen del SO y el navegador. Pulsa ↺ si la lista no carga.",
             "url_missing": "⚠️ URL del endpoint faltante.",
             "test_sending": "⏳ Enviando…",
-            "test_ok": "✅ Respuesta {code} — comprueba que el altavoz haya hablado."
+            "test_ok": "✅ Respuesta {code} — comprueba que el altavoz haya hablado.",
+            "heard_question": "¿Has escuchado la voz?",
+            "heard_yes": "Sí, la escuché",
+            "heard_no": "No, no escuché nada",
+            "test_ok_kiosk": "TTS funcionando.",
+            "test_fail_steps": "Comprueba: 1) el volumen del multimedia no es 0; 2) Google Text-to-Speech está instalado y actualizado; 3) el paquete de voz español está descargado en la configuración TTS de Android."
         },
         "language": {
             "title": "🌐 Idioma",

translations/fr.json

@@ -694,7 +694,12 @@
             "voices_hint": "Les voix disponibles dépendent du système d'exploitation et du navigateur. Appuyez sur ↺ si la liste ne se charge pas.",
             "url_missing": "⚠️ URL de l'endpoint manquante.",
             "test_sending": "⏳ Envoi…",
-            "test_ok": "✅ Réponse {code} — vérifiez que le haut-parleur a parlé."
+            "test_ok": "✅ Réponse {code} — vérifiez que le haut-parleur a parlé.",
+            "heard_question": "Avez-vous entendu la voix ?",
+            "heard_yes": "Oui, je l'ai entendu",
+            "heard_no": "Non, je n'ai rien entendu",
+            "test_ok_kiosk": "TTS fonctionne.",
+            "test_fail_steps": "Vérifiez : 1) le volume média n'est pas 0 ; 2) Google Text-to-Speech est installé et mis à jour ; 3) le pack vocal français est téléchargé dans les paramètres TTS Android."
         },
         "language": {
             "title": "🌐 Langue",

translations/it.json

@@ -701,7 +701,12 @@
             "voices_hint": "Le voci disponibili dipendono dal sistema operativo e dal browser. Su macOS/iOS è disponibile la voce Paola (italiano). Premi ↺ se la lista non si carica.",
             "url_missing": "⚠️ URL endpoint mancante.",
             "test_sending": "⏳ Invio in corso…",
-            "test_ok": "✅ Risposta {code} — controlla che l'altoparlante abbia parlato."
+            "test_ok": "✅ Risposta {code} — controlla che l'altoparlante abbia parlato.",
+            "heard_question": "Hai sentito la voce?",
+            "heard_yes": "Sì, ho sentito",
+            "heard_no": "No, non ho sentito",
+            "test_ok_kiosk": "TTS funzionante.",
+            "test_fail_steps": "Controlla: 1) volume media del dispositivo non sia 0; 2) Google Text-to-Speech installato e aggiornato; 3) pacchetto vocale italiano scaricato nelle impostazioni TTS Android."
         },
         "language": {
             "title": "🌐 Lingua / Language",