Fix: Remove accidental leading whitespace in app.py causing IndentationError

Feat: Add conversational chat mode for short messages using LLM

Fix: Switch to FastAPI/Uvicorn for better HF Spaces compatibility and running status detection

Fix: Replace dummy server with Flask to satisfy HF Spaces 'Running' status

Fix: Swap execution order - Run web server in main thread to ensure HF detects running status

Fix: Add dummy HTTP server (app.py) to satisfy HF Spaces 'Running' check