First npm release. Published as `differens` and `@ossl/differens-cli`.

GumTree-lineage matching core, tree-sitter code adapter with TypeScript,
Python, Rust and Go extractors, JSON/YAML/TOML adapters, git working-tree,
commit-range and directory diffing, a cross-file correlator, and terminal,
markdown, json and llm output. Per-file diffs run on a process pool.
Runs on Node 18.17+.