All write paths (upsert_node, upsert_provenance, delete_node,
rename_node, ingest_units) now hold StoreLock across the full
refresh→check→write cycle. This prevents the race where two
concurrent processes both see a key as "new" and create separate
UUIDs for it.
Adds append_nodes_unlocked() and append_relations_unlocked() for
callers already holding the lock. Adds refresh_nodes() to replay
log tail under lock before deciding create vs update.
Also adds find_duplicates() for detecting existing duplicates
in the log (replays full log, groups live nodes by key).
poc-daemon (notification routing, idle timer, IRC, Telegram) was already
fully self-contained with no imports from the poc-memory library. Now it's
a proper separate crate with its own Cargo.toml and capnp schema.
poc-memory retains the store, graph, search, neuro, knowledge, and the
jobkit-based memory maintenance daemon (daemon.rs).
Co-Authored-By: ProofOfConcept <poc@bcachefs.org>
