Adds speech-to-text dictation to the web and desktop composer. Audio
streams to an environment that runs an opt-in local model (sherpa-onnx
with Parakeet v3, Whisper turbo, or Moonshine base), so remote browsers
can dictate through the machine they are connected to.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>