Fix permission error: create upload directories before switching to user

Dockerfile

@@ -100,7 +100,11 @@ RUN python -c "import insightface; print('InsightFace installed successfully')"
 COPY --chown=user:user api_server.py /app/
 COPY --chown=user:user DeepFakeAI/ /app/DeepFakeAI/
 
-# Switch to user (upload directories will be created by api_server.py on startup)
+# Create upload directories with proper permissions before switching to user
+RUN mkdir -p /app/uploads/source_images /app/uploads/target_videos /app/uploads/result_videos && \
+    chown -R user:user /app/uploads
+
+# Switch to user (upload directories already created with proper permissions)
 USER user
 ENV PATH="/home/user/.local/bin:$PATH"