feat(web): voice input — record, check the recognised text, send

Microphone button in the chat composer and in free-text steps. The browser
records 16 kHz mono WAV (no server-side ffmpeg), /me/{token}/stt transcribes,
the text lands in the field for the patient to check and edit — never sent
automatically, so safety and scrub() apply on send. Hidden when the server has
voice input off or the browser lacks a microphone API. nginx: 4 MB body limit.

Refs #117

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

web/src/voice/recorder.ts

@@ -11,7 +11,9 @@ type WindowWithWebkit = Window & { webkitAudioContext?: typeof AudioContext };
 
 export function voiceSupported(): boolean {
   const w = window as WindowWithWebkit;
-  return typeof navigator.mediaDevices?.getUserMedia === "function" && Boolean(window.AudioContext || w.webkitAudioContext);
+  return (
+    typeof navigator.mediaDevices?.getUserMedia === "function" && Boolean(window.AudioContext || w.webkitAudioContext)
+  );
 }
 
 export class Recorder {