feat(voice): per-account choice between Whisper and the browser; STT_ALLOW_BROWSER

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

frontend/src/lib/api.ts

@@ -301,6 +301,7 @@ export const api = {
     notifyBeforeMinutes?: number;
     notificationSettings?: NotificationSettings;
     doneRetentionDays?: number;
+    voiceInput?: '' | 'browser';
   }): Promise<User> {
     return request<User>('/api/v1/auth/settings', {
       method: 'PATCH',