feat: Whisper model selector + 16kHz mono recording

- App: AudioSamplingRateAndroid 16000 + AudioChannelsAndroid 1
  → Whisper bekommt direkt sein Ziel-Format, kein Resample mehr
- Bridge: STTEngine.reload() laedt Modell zur Laufzeit neu
  (tiny/base/small/medium/large-v3)
- Bridge: Config-Message triggert Hot-Reload wenn whisperModel sich aendert
- Bridge: Default auf 'medium' (besser als 'small' bei aehnlicher Latenz)
- Diagnostic: Neue Sektion "Whisper (Spracherkennung)" mit Dropdown,
  auto-save bei Auswahl, beim Laden wird der gespeicherte Wert gesetzt
- Diagnostic/Server: send_voice_config merged whisperModel in voice_config.json
- aria.env.example: WHISPER_MODEL + WHISPER_LANGUAGE dokumentiert

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

diagnostic/index.html

@@ -499,6 +499,30 @@
       </div>
     </div>
 
+    <!-- Whisper (STT) -->
+    <div class="settings-section">
+      <h2>Whisper (Spracherkennung)</h2>
+      <div style="font-size:11px;color:#8888AA;margin-bottom:8px;">
+        Aenderungen werden sofort an die Bridge gesendet und das Modell neu geladen
+        (kann bei medium/large 10-30s dauern — waehrend dieser Zeit ist STT kurz pausiert).
+      </div>
+      <div class="card" style="max-width:500px;">
+        <div style="display:flex;align-items:center;gap:12px;margin-bottom:8px;">
+          <label style="color:#8888AA;font-size:12px;min-width:80px;">Modell:</label>
+          <select id="diag-whisper-model" onchange="sendVoiceConfig()" style="flex:1;background:#1E1E2E;color:#fff;border:1px solid #2A2A3E;border-radius:6px;padding:6px 10px;font-size:13px;">
+            <option value="tiny">tiny (39MB, schnell, niedrige Qualitaet)</option>
+            <option value="base">base (74MB, schnell, ok)</option>
+            <option value="small">small (244MB, mittel)</option>
+            <option value="medium" selected>medium (769MB, gut — Empfehlung)</option>
+            <option value="large-v3">large-v3 (1.5GB, beste Qualitaet, langsam auf CPU)</option>
+          </select>
+        </div>
+        <div style="font-size:10px;color:#555570;">
+          Tipp: <code>medium</code> ist der beste Kompromiss fuer CPU. <code>large-v3</code> nur bei GPU sinnvoll.
+        </div>
+      </div>
+    </div>
+
     <!-- Highlight-Trigger -->
     <div class="settings-section">
       <h2>Highlight-Trigger</h2>
@@ -763,6 +787,11 @@
           }
           xttsSelect.value = xttsVoice;
           toggleXTTSPanel();
+          // Whisper-Modell wiederherstellen (falls gesetzt)
+          if (msg.whisperModel) {
+            const wSel = document.getElementById('diag-whisper-model');
+            if (wSel) wSel.value = msg.whisperModel;
+          }
           return;
         }
 
@@ -1404,7 +1433,8 @@
       const speedThorsten = parseFloat(document.getElementById('diag-speed-thorsten').value);
       const ttsEngine = document.getElementById('diag-tts-engine').value;
       const xttsVoice = document.getElementById('diag-xtts-voice').value;
-      send({ action: 'send_voice_config', defaultVoice, highlightVoice, ttsEnabled, speedRamona, speedThorsten, ttsEngine, xttsVoice });
+      const whisperModel = document.getElementById('diag-whisper-model').value;
+      send({ action: 'send_voice_config', defaultVoice, highlightVoice, ttsEnabled, speedRamona, speedThorsten, ttsEngine, xttsVoice, whisperModel });
     }
 
     // ── Highlight-Trigger ────────────────────────

diagnostic/server.js

@@ -1253,7 +1253,11 @@ wss.on("connection", (ws) => {
         handleGetVoiceConfig(ws);
       } else if (msg.action === "send_voice_config") {
         // Stimmen-Config persistent speichern + an Bridge via RVS senden
+        // Bestehende Config lesen um Felder zu mergen die dieser Call nicht setzt
+        let existing = {};
+        try { existing = JSON.parse(fs.readFileSync("/shared/config/voice_config.json", "utf-8")); } catch {}
         const voiceConfig = {
+          ...existing,
           defaultVoice: msg.defaultVoice || "ramona",
           highlightVoice: msg.highlightVoice || "thorsten",
           ttsEnabled: msg.ttsEnabled !== false,
@@ -1262,12 +1266,13 @@ wss.on("connection", (ws) => {
           speedRamona: msg.speedRamona || 1.0,
           speedThorsten: msg.speedThorsten || 1.0,
         };
+        if (msg.whisperModel !== undefined) voiceConfig.whisperModel = msg.whisperModel;
         try {
           fs.mkdirSync("/shared/config", { recursive: true });
           fs.writeFileSync("/shared/config/voice_config.json", JSON.stringify(voiceConfig, null, 2));
         } catch {}
         sendToRVS_raw({ type: "config", payload: voiceConfig, timestamp: Date.now() });
-        log("info", "server", `Voice-Config gespeichert+gesendet: default=${voiceConfig.defaultVoice}, highlight=${voiceConfig.highlightVoice}, tts=${voiceConfig.ttsEnabled}`);
+        log("info", "server", `Voice-Config gespeichert+gesendet: default=${voiceConfig.defaultVoice}, whisper=${voiceConfig.whisperModel || "-"}`);
       } else if (msg.action === "get_triggers") {
         handleGetTriggers(ws);
       } else if (msg.action === "save_triggers") {