Fix: audio_output Hang + Stimme auf Seraphina

- speak() hing weil pygame.time.wait() die asyncio Event-Loop blockierte.
  Fix: time.sleep(0.05) statt pygame.time.wait() im Playback-Loop.
- asyncio.new_event_loop() statt asyncio.run() — thread-sicher, kein
  "event loop already running" in Worker-Threads.
- _speak_lock verhindert parallele TTS-Aufrufe.
- Stimme: de-DE-SeraphinaMultilingualNeural als Default (modern, weiblich,
  multilingual neural). Dropdown in Settings mit allen DE/EN Optionen.
- speak()-Signatur: voice + rate als Parameter (statt config-Import).

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

client/hermes-voice/main.py

@@ -259,8 +259,13 @@ class SettingsWindow(ctk.CTkToplevel):
 
         label("TTS Stimme")
         self._voice = dropdown("tts_voice", [
-            "de-DE-KillianNeural", "de-DE-SeraphinaMultilingualNeural",
-            "de-DE-ConradNeural", "en-US-AndrewNeural", "en-US-AriaNeural",
+            "de-DE-SeraphinaMultilingualNeural",
+            "de-DE-AmalaNeural",
+            "de-DE-KatjaNeural",
+            "de-DE-KillianNeural",
+            "de-DE-ConradNeural",
+            "en-US-AriaNeural",
+            "en-US-JennyNeural",
         ])
 
         label("Whisper Modell")