perf(db): NativeDatabase napi-rs class for rusqlite connection lifecycle (6.13) (#666)

* perf(db): add NativeDatabase napi-rs class for rusqlite connection lifecycle (6.13)

Foundation for moving all DB operations to rusqlite on the native engine
path. Creates a persistent rusqlite::Connection holder exposed to JS,
handling schema migrations and build metadata KV — eliminating redundant
per-call connection open/close in the native build pipeline.

* fix(rust): resolve NativeDatabase compilation error and harden init_schema (#666)

- Fix E0507 in close(): use (*self.conn).take() to deref through SendWrapper
  and call Option::take instead of SendWrapper::take which consumes self
- Wrap each migration in an explicit transaction so a mid-migration crash
  rolls back cleanly instead of leaving the DB in an unrecoverable state
- Add ORDER BY rowid DESC LIMIT 1 to schema_version query to handle
  potential duplicate rows deterministically
- Document pragma() as read-only with guidance to use exec() for write PRAGMAs

* fix(build): remove redundant String() conversion in setBuildMeta (#666)

All values in the metadata object are already strings (explicitly coerced
via String() in the object literal), so the outer .map() String() wrapper
was a no-op.

Author: carlos-alm

crates/codegraph-core/src/lib.rs

@@ -10,6 +10,7 @@ pub mod extractors;
 pub mod import_resolution;
 pub mod incremental;
 pub mod insert_nodes;
+pub mod native_db;
 pub mod parallel;
 pub mod parser_registry;
 pub mod roles_db;