feat: references parser + session v2 — corpus matching, citeIndex, new schema models

feat: top-10 retrieval pool; plaintext/markdown manuscript input

feat: compact local corpus — fp16 faiss index + text-only parquet

fix: epsilon guard for zero-distance similarity conversion

fix: use arxiv_id column (not ads_id) for arXiv link in LitPaper

feat: corpus wrapper and per-paragraph retrieval

feat: keyword extraction and pathfinder keyword weighting