A stable façade so another Python app can use arborist as a
content-addressed / Merkle / audit-chained store without the CLI or a
wire protocol. Import from arborist.embed, not internal modules, so
refactors don't break embedders.
Surface: open_store(path), ingest_documents(conn, docs), search(conn, q),
plus re-exported Document/Edge/Source/Hit/IngestStats. Core only
(python+sqlite3) — no extras. _IterableSource adapts a plain doc iterable
into the Source contract.
This is the seam for using arborist as neopig's optional provenance
backend: neopig produces Documents from crawled pages, arborist gives
content-dedup (document_root) + FTS5 + an append-only audit chain
alongside neopig's existing md5/FileVault storage. Docs in
docs/embedding.md. 6 tests pin open/ingest/dedup/idempotence/edges/search.
