feat: full-page language switch (UK/EN)

feat: answer-language toggle (UK/EN) for judges

fix: build on llama.cpp ubuntu24 base, resolves glibc mismatch

fix: huggingface-cli removed in hub 1.x, use hf download

Paper Decoder v1: base model end-to-end (G1)

Paper Decoder v1: base model end-to-end (G1)

initial commit