Note type metadata

Relevant to #814

We need to have similar metadata for note storage as we have for account storage.

Look at the account storage metadata implementation referenced in issue #814 to understand the pattern. Examine the note storage module to see where metadata should be added. The change likely involves defining metadata structures and integrating them into the note storage system. Check for existing tests related to note storage to understand the testing approach.

Written by the indexing model from the issue text.