Summary

• fix undefined user_id in /api/ask by initializing it from get_current_user_id()
• preserve orchestrator-returned sources in ask_internal() instead of clearing them
• keep the change focused to API correctness with no behavior changes outside the bugfix scope

Test plan

• py -3 -m py_compile main.py
• Verify /api/ask no longer references undefined user_id
• Verify ask_internal() returns sources from orchestration path

Refs #7