refactor(bank): split monolithic store into focused modules; fix locker grant for attachments
- Split BankBaseStore into SessionManager, Messenger, Model, Store, Validator
- Extract validation logic into BankValidator with try/catch and per-action methods
- Remove duplicate notifications from transaction actions
- Update event handlers to call validator first, forward context to store/session
- Fix locker grantItems: add missing 'attachment' category mapping to 'item'
- Fix locker grantItems: replace exitWith with if/else to prevent skipping remaining items
Co-Authored-By: Oz <oz-agent@warp.dev>
6c0ce9e867