fix: nginx substitutions

deploy/docker-entrypoint.sh

@@ -1,13 +1,8 @@
 #!/bin/sh
 set -e
 
-# Ensure SERVER_NAME is set
-if [ -z "$SERVER_NAME" ]; then
-  echo "[entrypoint] SERVER_NAME is not set. Using default value: localhost"
-  SERVER_NAME="localhost"
-else
-  echo "[entrypoint] Using SERVER_NAME=$SERVER_NAME"
-fi
+SERVER_NAME="${SERVER_NAME:-$(hostname -f 2>/dev/null || hostname)}"
+export SERVER_NAME
 
 # Prepare BASIC_AUTH_DIRECTIVES
 if [ "$ENABLE_BASIC_AUTH" = "true" ]; then