Support incremental updates

Running this script can take several hours against a large notes database.

Would be neat if it could run against just the notes that have been modified since it last ran. Could pull the max `updated` date and then keep on looping until it finds one modified before then.

Problem is I don't actually know what order it iterates over the notes in.

Start by locating the script entry point and the code that iterates over Apple Notes and writes to the SQLite database. Check how the notes' `updated` date is exposed and what iteration order is available. Done means a rerun processes only notes modified since the previous run while still handling the stopping condition correctly.

Written by the indexing model from the issue text.