Add runtime UID/GID adjustment to match host workspace owner

Dockerfile

@@ -31,6 +31,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     less \
     vim-tiny \
     sudo \
+    gosu \
     locales \
     procps \
     unzip \
@@ -103,9 +104,10 @@ RUN mkdir -p /workspace \
 
 # ── Entrypoint ────────────────────────────────────────────────────────
 COPY entrypoint.sh /usr/local/bin/entrypoint.sh
-RUN chmod +x /usr/local/bin/entrypoint.sh
+COPY entrypoint-user.sh /usr/local/bin/entrypoint-user.sh
+RUN chmod +x /usr/local/bin/entrypoint.sh /usr/local/bin/entrypoint-user.sh
 
-USER ${USER_NAME}
+# Start as root — entrypoint adjusts UID/GID then drops to developer
 WORKDIR /workspace
 
 ENTRYPOINT ["entrypoint.sh"]