Fix overlay service permission issue by running as root for shared volume access

squashkiwi-streaming/config/overlay/Dockerfile

@@ -20,10 +20,11 @@ COPY overlay_service.py .
 # Create recordings directory
 RUN mkdir -p /recordings
 
-# Run as non-root user
+# Create user but don't switch to it - need root for shared volume
 RUN useradd -m -s /bin/bash overlay && \
     chown -R overlay:overlay /app /recordings
-USER overlay
+# Running as root to access shared /tmp volume
+# USER overlay
 
 # Health check
 HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \