Dockerfile: copy all Python modules, not just app.py

Previous COPY hardcoded app.py only, which broke the moment app.py
imported sibling leaderboard.py: the new module never made it into the
image and the runtime hit ModuleNotFoundError. Switching to *.py picks
up every Python file in AI4Engineering/ (currently app.py +
leaderboard.py; submit.py lands next), so future module additions
don't need a Dockerfile bump.

Dockerfile

@@ -55,7 +55,7 @@ RUN useradd -m -u 1000 user \
     && chown -R user:user /home/user/app
 USER user
 WORKDIR /home/user/app
-COPY --chown=user:user app.py results.jsonl ./
+COPY --chown=user:user *.py results.jsonl ./
 
 EXPOSE 7860
 CMD ["python", "app.py"]