Add test interface HTML to Docker image

- Copy test_interface.html to /app/ in Docker image
- Fixes 404 error on /test endpoint

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Dockerfile

@@ -16,5 +16,8 @@ ENV HF_HOME=/data/huggingface
 RUN mkdir -p /data /app/models /app/knowledge_db /data/huggingface/hub /data/huggingface/transformers && \
     chmod -R 777 /data /app/models /app/knowledge_db
 
+# Copy test interface (needed for /test endpoint)
+COPY test_interface.html /app/
+
 EXPOSE 8000
 CMD ["python", "main.py"]