Two review findings on #807/#812:
- retrieve() and trace_lineage() were routed through transaction()'s
BEGIN IMMEDIATE, so plain reads took SQLite's writer lock and
serialized behind every other read/write, defeating the WAL
concurrency this PR was meant to add. They now use a dedicated
_read_connection() (configured, no explicit BEGIN).
- track_entity()/track_chunk() swallowed all internal storage
exceptions unconditionally, so a single item's failure inside
track_entities_batch()/track_chunks_batch()'s shared transaction
never reached the batch loop's per-item except, inflating
tracked_count for entries that were never persisted. Both now
re-raise when called with a shared _conn (batch context) while
still degrading gracefully on standalone calls.
Added regression tests for both, corrected the CHANGELOG entry and
docs that described the prior (overly broad) behavior.
Sameer6305