fix(downloader): run as root to fix permission denied on models volume

The curlimages/curl image drops to non-root curl_user (uid 100) by
default, but the models named volume is created root-owned by Docker,
so writes into it failed with 'Permission denied'.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Q2CR8yawSf7pwAVYnjwFea

docker-compose.yml

@@ -41,6 +41,9 @@ services:
   downloader:
     image: curlimages/curl:latest
     profiles: ["tools"]
+    # ponytail: named volume is created root-owned; curl_user (uid 100) can't
+    # write into it otherwise, so run as root for this one-off job.
+    user: root
     volumes:
       - models:/models
     entrypoint: ["sh", "-c"]