Set DB_PATH environment variable in Dockerfile for explicit database location

Dockerfile

@@ -34,6 +34,8 @@ ENV PYTHONUNBUFFERED=1
 ENV PORT=7860
 ENV OMP_NUM_THREADS=1
 ENV MKL_NUM_THREADS=1
+ENV DB_PATH=/tmp/sessions.db
+ENV FAISS_INDEX_PATH=/tmp/embeddings.faiss
 
 # Health check
 HEALTHCHECK --interval=30s --timeout=30s --start-period=120s --retries=3 \