Track pt files with LFS

Deploy Maia3 Chess Prediction API - Chessformer 3M inference server

Update Stockfish 16 and add debug logging

Use universal Stockfish binary

Use apt stockfish for reliability

Add debug path check to health endpoint

Fix engine path search and remove finally bug

Remove Lc0 download, use fallback mode

Fix Dockerfile - remove COPY for missing folders

Add backend files

initial commit