fix docker build missing readme

backend/Dockerfile

@@ -6,11 +6,17 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     build-essential \
     && rm -rf /var/lib/apt/lists/*
 
-COPY pyproject.toml .
+COPY pyproject.toml readme.md ./
 
 RUN pip install --no-cache-dir .
 
-COPY . .
+# Create non-root user for security
+RUN addgroup --system --gid 1001 python && \
+    adduser --system --uid 1001 --gid 1001 appuser
+
+COPY --chown=appuser:python . .
+
+USER appuser
 
 EXPOSE 8000