Catalog inspection and statistics

Database::create_directory(&["app", "team"]) provisions a catalog directory hierarchy. Directories organize schemas; they are not storage paths and are not graph nodes.

Database::with_catalog exposes a catalog view inside a statement snapshot. Catalog entries carry stable object IDs, kinds, immutable definitions and commit versions. Inspecting the catalog does not mutate session selection.

Database::statistics() reports commits, conflicts, lock-wait time, recovery/checkpoint time, busy checkpoints and log bytes. Counts are process-local rather than a cluster-wide monitoring history.

Database::checkpoint() requests an idle checkpoint and may return Busy while a statement or transaction in any cooperating process holds a snapshot. See checkpointing.

Generate Rust API documentation from the checkout with cargo doc --workspace --no-deps --locked --open. This uses the exact code revision you are building instead of assuming a published crate version.