Integrates @ricky0123/vad-web's MicVAD as an optional voice activity detector
alongside the noise gate. When enabled, the Silero ONNX model classifies each
audio frame as speech or silence; silence frames mute the worklet's output via
a new VAD gate message. VAD is wired into Publisher.ts alongside the existing
noise gate transformer. Vite is configured to copy the worklet bundle, ONNX
model, and ORT WASM files to /vad/ so they're reachable at runtime.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
