fix: increase VAD silence to 800ms, slow TTS to 0.85x, lower threshold to 0.4

--min_silence_ms 800 (was 500ms — still cutting mid-word)
--min_speech_ms 300 (was 250ms)
--thresh 0.4 (was 0.5 — even more sensitive)
--kokoro_speed 0.85 (was 1.0 — TTS was racing through text)

Dockerfile

@@ -19,7 +19,7 @@ CMD speech-to-speech \
      --llm_backend responses-api \
      --tts kokoro \
      --kokoro_voice af_heart \
-     --kokoro_speed 1.0 \
+     --kokoro_speed 0.85 \
      --model_name "google/gemma-4-31B-it:cerebras" \
      --responses_api_base_url "https://router.huggingface.co/v1" \
      --responses_api_api_key "$HF_TOKEN" \
@@ -27,8 +27,8 @@ CMD speech-to-speech \
      --enable_live_transcription \
      --mode realtime \
      --num_pipelines 3 \
-     --min_silence_ms 500 \
-     --min_speech_ms 250 \
-     --thresh 0.5 \
+     --min_silence_ms 800 \
+     --min_speech_ms 300 \
+     --thresh 0.4 \
      --ws_host 0.0.0.0 \
      --ws_port 7860