Add opt-in GUI and audio support

Containerfile

@@ -3,11 +3,15 @@
 FROM docker.io/library/debian:stable-slim
 
 # Base tools Claude Code relies on. Add project-wide tools here (python3, nodejs, ...).
+# The second line is for GUI=1 / AUDIO=1: OpenGL drivers, a font, PulseAudio client.
 RUN apt-get update \
  && apt-get install -y --no-install-recommends \
       ca-certificates curl git ripgrep less procps openssh-client \
+      libgl1-mesa-dri fonts-dejavu-core libpulse0 libasound2-plugins \
  && rm -rf /var/lib/apt/lists/* \
- && useradd -m -u 1000 -s /bin/bash claude
+ && useradd -m -u 1000 -s /bin/bash claude \
+ && install -d -m 700 -o claude -g claude /run/user/1000 \
+ && printf 'pcm.!default pulse\nctl.!default pulse\n' > /etc/asound.conf
 
 # Native Claude Code binary, installed system-wide (not in $HOME) so that image
 # rebuilds update it even though /home/claude is a persistent volume.
@@ -17,7 +21,8 @@ RUN curl -fsSL https://claude.ai/install.sh | HOME=/tmp/cc bash \
 
 # Updates come from rebuilding the image, not from in-container self-updates.
 ENV DISABLE_AUTOUPDATER=1 \
-    PATH=/home/claude/.local/bin:$PATH
+    PATH=/home/claude/.local/bin:$PATH \
+    XDG_RUNTIME_DIR=/run/user/1000
 
 USER claude
 WORKDIR /home/claude