Claude Code: Add defensive mkdir for /data/frontend in entrypoint.sh

- Create /data/frontend at runtime before uvicorn starts
- Ensures directory exists even if Dockerfile COPY fails

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

entrypoint.sh

@@ -2,6 +2,9 @@
 set -e
 # Entrypoint for HuggingClaw - Cain
 
+# Ensure /data/frontend exists (defensive: created at build time, but verify at runtime)
+mkdir -p /data/frontend
+
 echo "=========================================="
 echo "Cain Starting..."
 echo "=========================================="