Update Dockerfile

Dockerfile

@@ -1,10 +1,11 @@
 FROM linuxserver/heimdall
 
-# Create custom user (matching PUID/PGID)
-RUN groupadd -g 1000 user && \
-    useradd -u 1000 -g user -d /app user && \
-    usermod -a -G abc user
-
-# Set environment variables
+# Use environment variables to control permissions
 ENV PUID=1000
-ENV PGID=1000
+ENV PGID=1000
+
+# Modify existing abc user instead of creating new
+RUN \
+  usermod -l newusername abc && \
+  groupmod -n newgroupname abc && \
+  usermod -d /app -m newusername