admin-api antispam stat endpoint not respecting Accept-Encoding

[mgkeeley]

The /api/v1/system/antispam/stat endpoint is always using Content-Encoding: zstd, even when Accept-Encoding: gzip, deflate is set.

This is causing a "Failed to fetch" error in the web ui.

VARIANT="grommunio appliance"
VARIANT_ID="appliance"
VERSION_ID="16.0"
VERSION="2026.06.1"

To reproduce:

curl --url 'http://localhost:8080/api/v1/system/antispam/stat' -H 'Accept-Encoding: gzip, deflate' -b 'grommunioAuthJwt=REDACTED' --output /dev/null -v 2>&1 | grep "Content-Encoding"
< Content-Encoding: zstd