The `notes.sfld` column in the `collection.anki2` database has type `integer`, even though it contains text. This is [something SQLite allows](https://dba.stackexchange.com/questions/106364/text-string-stored-in-sqlite-integer-column) and was done to allow integer values to sort numerically. Add a comment explaining this.
committing the Protobuf implementation for posterity, but will replace it with json, as Protobuf measures about 6x slower for some workloads like 'select * from notes'