Improve entrypoint script creation in Dockerfile

Dockerfile

@@ -28,7 +28,12 @@ RUN mkdir -p uploads results
 
 # Handle Firebase credentials from environment variable (for Hugging Face Spaces secrets)
 # This allows the credentials to be passed as a secret and written to file at runtime
-RUN echo '#!/bin/bash\nif [ -n "$FIREBASE_CREDENTIALS" ]; then echo "$FIREBASE_CREDENTIALS" > colorize-662df-firebase-adminsdk-fbsvc-e080668793.json; fi\nexec "$@"' > /entrypoint.sh && chmod +x /entrypoint.sh
+RUN echo '#!/bin/bash' > /entrypoint.sh && \
+    echo 'if [ -n "$FIREBASE_CREDENTIALS" ]; then' >> /entrypoint.sh && \
+    echo '  echo "$FIREBASE_CREDENTIALS" > colorize-662df-firebase-adminsdk-fbsvc-e080668793.json' >> /entrypoint.sh && \
+    echo 'fi' >> /entrypoint.sh && \
+    echo 'exec "$@"' >> /entrypoint.sh && \
+    chmod +x /entrypoint.sh
 
 # Expose port (Hugging Face Spaces uses port 7860)
 EXPOSE 7860