Nextcloud returns poll/login URLs using its internal hostname (e.g.
http://localhost/login/v2/poll) which is unreachable from the MCP
server container in Docker networks. Rewrite the poll endpoint's
origin to use the configured NEXTCLOUD_HOST so server-side polling
works correctly.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>