`close` fn can silently leave SQLite connections open

[Ramblurr]

The pool's :close function calls sqlite3_close without finalizing cached statements or checking the return code. SQLite can return SQLITE_BUSY, leaving the connection open without reporting an error.

Consider using sqlite3_close_v2, which supports deferred cleanup and is designed for use in garbage-collected languages. Cached statements still need to be finalized so SQLite can release th connection.

ref https://sqlite.org/c3ref/close.html

Could we expose a single (d/close! db) that does something like:

• Finalizes cached statements and closes each distinct pool once.
• Uses sqlite3_close_v2 and checks return codes.
• Is idempotent