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

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

docker-compose.yml

@@ -56,6 +56,7 @@ services:
       - STT_LANGUAGE=${STT_LANGUAGE:-de}
       - STT_API_KEY=${STT_API_KEY:-}
       - STT_DISABLED=${STT_DISABLED:-false}
+      - STT_ALLOW_BROWSER=${STT_ALLOW_BROWSER:-true}
       - STT_MAX_SECONDS=${STT_MAX_SECONDS:-600}
       - STT_MAX_UPLOAD_MB=${STT_MAX_UPLOAD_MB:-25}
       - STT_MAX_PARALLEL=${STT_MAX_PARALLEL:-1}