All 11 Python runners previously executed as root. Bring them into parity
with langroid (the one Python package that already had the pattern):
- Create uid/gid 1001 'app' user/group before any COPY
- Add --chown=app:app to runner-stage COPY directives
- USER app before EXPOSE/CMD
- langgraph-python: add the missing COPY --from=frontend /app/public line
(every other Python package has it) plus an empty public/.gitkeep so
the copy resolves
Packages touched: ag2, agno, claude-sdk-python, crewai-crews, google-adk,
langgraph-fastapi, langgraph-python, llamaindex, ms-agent-python,
pydantic-ai, strands.
Jordan Ritter