Add a pulsing halo behind the stop button that scales with the
microphone input level, giving real-time feedback that recording is
active and the mic is picking up sound.
- use-dictation: meter the captured MediaStream via AudioContext +
AnalyserNode (analyser only, never connected to destination), compute
a smoothed RMS audioLevel (0..1) in a requestAnimationFrame loop, and
tear the meter down on every recording-end path (stop/cancel/auto-stop/
unmount); meter failure is non-fatal to recording
- mic-button: render a translucent red halo whose scale follows
audioLevel; honor prefers-reduced-motion with a static halo
- stop(): recover and release resources when no live recorder remains
- fix unhandled rejection from AudioContext.resume()
55625874c5