fix: add do_lower_case=True to tokenizer (v1.1.1)

chore: gitignore cluster/, track test vocab fixture

refactor: extract shared case study utils and move data to tracked paths

fix: handle >512 token sentences and add MPS device support

test: add contextual nearest neighbors case study (Bamman & Burns §4.4)

feat: make benchmarks model-agnostic with --model-path option

test: add WSD case study reproduction (Bamman & Burns Table 2)

test: add POS tagging case study reproduction (Bamman & Burns Table 1)

test: add infilling case study reproduction (Bamman & Burns Table 3)

Fix tokenizer ID offset: reserve IDs 0-4 for BERT special tokens

Initial: HF-compatible Latin BERT tokenizer (Bamman & Burns 2020)