Add Rust module (pubmed.rs) and shell script (pubmed_discover.sh) for
fetching biomedical abstracts from NCBI E-utilities, detecting emerging
topics via rare MeSH term combinations, identifying contradictions
through shared MeSH + opposing sentiment signals, and optionally pushing
discoveries to the π.ruv.io brain API.
Tested against real PubMed data: CRISPR gene therapy (10 emerging topics)
and metformin cancer treatment (5 contradiction signals detected).
https://claude.ai/code/session_01UWE22wnsZRSHKhT4h4Axby
