fix: use Silero v5 model for 32ms frames and lower default thresholds

The legacy model is hardcoded to 1536 samples (96ms frames); v5 uses 512
samples (32ms), reducing gate open latency by 3x. Also lower default
positive/negative thresholds to 0.2/0.1 so the gate opens at the first
sign of speech rather than waiting for high model confidence.

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

vite.config.ts

@@ -79,6 +79,10 @@ export default ({
           src: "node_modules/@ricky0123/vad-web/dist/silero_vad_legacy.onnx",
           dest: "vad",
         },
+        {
+          src: "node_modules/@ricky0123/vad-web/dist/silero_vad_v5.onnx",
+          dest: "vad",
+        },
         {
           src: "node_modules/onnxruntime-web/dist/*.wasm",
           dest: "vad",