Revert LLM back to nvidia/nemotron-3-nano-30b-a3b, update UI description

Switch LLM to google/gemma-4-31b-it, update all model descriptions in UI

Switch embedding model from Google to NVIDIA NIM (llama-nemotron-embed-1b-v2)

update name

update home

without comment

1.0

HF-Deployment: Initial commit