chore: modernize Dockerfile for Java 21, drop Tango infra assumptions

- Base image: adoptopenjdk/openjdk11 → eclipse-temurin:21-jre-alpine
- Remove -DTANGO_HOST and -server (no-op on modern JVM)
- Replace deprecated MAINTAINER with LABEL
- Config path and port now configurable via SS_CONFIG / SS_PORT env vars

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Ingvord

Dockerfile

@@ -1,19 +1,21 @@
-FROM adoptopenjdk/openjdk11:alpine-jre
+FROM eclipse-temurin:21-jre-alpine
 
-RUN apk add dumb-init
-MAINTAINER igor.khokhriakov@hzg.de
+RUN apk add --no-cache dumb-init
+
+LABEL maintainer="igor.khokhriakov@hzg.de"
 
 ARG JAR_FILE
 ADD target/${JAR_FILE} /app/bin/ss.jar
-
 ADD etc /app/etc
 
 RUN addgroup --system javauser && adduser -S -s /bin/false -G javauser javauser
 RUN chown -R javauser /app
 
 USER javauser
-
 WORKDIR /app
 
+ENV SS_CONFIG=/app/etc/StatusServer/conf/config.xml
+ENV SS_PORT=9190
+
 ENTRYPOINT ["/usr/bin/dumb-init", "--"]
-CMD java -jar -server -DTANGO_HOST=$TANGO_HOST /app/bin/ss.jar dev
+CMD java -jar /app/bin/ss.jar $SS_CONFIG $SS_PORT