feat: Bug-Runde + 5 App/Diagnostic-Features

Bugs:
- App Mute-/Auto-Playback: onMessage-Closure hielt stale ttsDeviceEnabled/
  ttsMuted → Mute wurde ignoriert + AsyncStorage-Load kam nicht durch.
  Fix via ttsCanPlayRef (live gespiegelt) statt Closure-Variablen.
- App Zombie-Recording: toggleWakeWord hat die laufende Aufnahme nicht
  gestoppt → audioService.recordingState blieb 'recording' → normaler
  Aufnahme-Button wirkungslos. Fix: await stopRecording() vor stop().
- Porcupine robuster: BuiltInKeywords-Enum Mapping mit String-Fallback,
  errorCallback fuer Runtime-Crashes (state zurueck auf off statt
  App-Crash), mehr Logging damit man beim naechsten Issue debuggen kann.

App-Features:
- MessageText Komponente: Text ist durchgehend selektierbar, erkennt
  URLs (http/https), E-Mails, Telefonnummern und macht sie anklickbar
  (oeffnet Browser / Mail-App / Android-Dialer via Linking).
- TTS-Wiedergabegeschwindigkeit pro Geraet einstellbar (Settings ->
  "Sprechgeschwindigkeit", 0.5-2.0 in 0.1-Schritten, Default 1.0).
  Wird als speed-Param an die F5-TTS-Bridge durchgereicht.

Bridge-Durchreichen:
- ChatScreen: speed aus AsyncStorage via ttsSpeedRef, an chat/audio/
  tts_request mitgeschickt
- aria-bridge: _next_speed_override wie voice_override, an xtts_request
  weitergereicht
- f5tts-bridge: speed-Param an F5TTS.infer() durchgereicht

Diagnostic-Feature:
- Voice-Preview-Button (Play-Icon) vor dem Delete-X in der Stimmen-Liste
- Modal mit Textfeld (Default-Beispieltext wird bei jedem Oeffnen neu
  gesetzt) und Play-Button
- Server sammelt audio_pcm Frames der Preview-Anfrage, baut WAV,
  schickt base64 zurueck, Browser spielt im <audio>-Tag ab
- 60s Timeout-Safety-Net

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

diagnostic/server.js

@@ -653,6 +653,9 @@ function connectRVS(forcePlain) {
           log("info", "rvs", `service_status ${svc} ${state}${model ? ` (${model})` : ""}`);
         }
         broadcast({ type: "service_status", payload: msg.payload });
+      } else if (msg.type === "audio_pcm" && msg.payload && _previewPending.size > 0) {
+        // PCM-Chunks einer laufenden Voice-Preview — sammeln + WAV bauen
+        _handlePreviewChunk(msg.payload);
       } else {
         log("debug", "rvs", `Nachricht: ${JSON.stringify(msg).slice(0, 150)}`);
       }
@@ -1465,6 +1468,8 @@ wss.on("connection", (ws) => {
         handleSaveTriggers(ws, msg.triggers || []);
       } else if (msg.action === "test_tts") {
         handleTestTTS(ws, msg.text || "Test");
+      } else if (msg.action === "preview_voice") {
+        handleVoicePreview(ws, msg.voice || "", msg.text || "Hallo.");
       } else if (msg.action === "check_tts") {
         handleCheckTTS(ws);
       } else if (msg.action === "check_desktop") {
@@ -1637,6 +1642,95 @@ async function handleSaveTriggers(clientWs, triggers) {
 }
 
 // ── TTS Diagnose (XTTS) ───────────────────────────────
+// ── Voice Preview ────────────────────────────────────────
+// Sammelt audio_pcm Chunks einer Preview-Anfrage, baut am Ende eine WAV
+// und schickt sie base64-kodiert an den Browser-Client.
+//
+// Map requestId → { clientWs, chunks: [Buffer], sampleRate, channels }
+const _previewPending = new Map();
+
+function _buildWavFromPcm(pcmBuf, sampleRate, channels) {
+  const bitsPerSample = 16;
+  const byteRate = sampleRate * channels * bitsPerSample / 8;
+  const blockAlign = channels * bitsPerSample / 8;
+  const dataSize = pcmBuf.length;
+  const header = Buffer.alloc(44);
+  header.write("RIFF", 0);
+  header.writeUInt32LE(36 + dataSize, 4);
+  header.write("WAVE", 8);
+  header.write("fmt ", 12);
+  header.writeUInt32LE(16, 16);            // subchunk1 size
+  header.writeUInt16LE(1, 20);             // PCM
+  header.writeUInt16LE(channels, 22);
+  header.writeUInt32LE(sampleRate, 24);
+  header.writeUInt32LE(byteRate, 28);
+  header.writeUInt16LE(blockAlign, 32);
+  header.writeUInt16LE(bitsPerSample, 34);
+  header.write("data", 36);
+  header.writeUInt32LE(dataSize, 40);
+  return Buffer.concat([header, pcmBuf]);
+}
+
+function _handlePreviewChunk(payload) {
+  const reqId = payload?.requestId || "";
+  const entry = _previewPending.get(reqId);
+  if (!entry) return;
+  if (payload.base64) {
+    try { entry.chunks.push(Buffer.from(payload.base64, "base64")); } catch {}
+  }
+  if (!entry.sampleRate && payload.sampleRate) entry.sampleRate = payload.sampleRate;
+  if (!entry.channels && payload.channels) entry.channels = payload.channels;
+  if (payload.final) {
+    _previewPending.delete(reqId);
+    try {
+      const pcm = Buffer.concat(entry.chunks);
+      const wav = _buildWavFromPcm(pcm, entry.sampleRate || 24000, entry.channels || 1);
+      const b64 = wav.toString("base64");
+      if (entry.clientWs && entry.clientWs.readyState === 1) {
+        entry.clientWs.send(JSON.stringify({
+          type: "voice_preview_audio",
+          base64: b64,
+          size: wav.length,
+        }));
+      }
+    } catch (err) {
+      if (entry.clientWs && entry.clientWs.readyState === 1) {
+        entry.clientWs.send(JSON.stringify({
+          type: "voice_preview_audio",
+          error: err.message,
+        }));
+      }
+    }
+  }
+}
+
+async function handleVoicePreview(clientWs, voice, text) {
+  try {
+    const requestId = crypto.randomUUID();
+    _previewPending.set(requestId, { clientWs, chunks: [], sampleRate: 0, channels: 0 });
+    // Timeout safety net
+    setTimeout(() => {
+      if (_previewPending.has(requestId)) {
+        _previewPending.delete(requestId);
+        if (clientWs && clientWs.readyState === 1) {
+          clientWs.send(JSON.stringify({
+            type: "voice_preview_audio",
+            error: "Timeout (60s) — keine Antwort vom f5tts-bridge",
+          }));
+        }
+      }
+    }, 60000);
+    log("info", "server", `Voice-Preview: voice="${voice}" text="${text.slice(0, 60)}"`);
+    sendToRVS_raw({
+      type: "xtts_request",
+      payload: { text, language: "de", requestId, voice, speed: 1.0 },
+      timestamp: Date.now(),
+    });
+  } catch (err) {
+    clientWs.send(JSON.stringify({ type: "voice_preview_audio", error: err.message }));
+  }
+}
+
 async function handleTestTTS(clientWs, text) {
   try {
     log("info", "server", `TTS-Test via XTTS: "${text}"`);