refactor: complete certificate deposit handling
- Strengthen deposit handling contract with required certDeposits map - Add missing certificates for Conway era deposit requirements - Standardize CertificateID assignment to uint(i) across all certificate types - Add helper functions: certRequiresDeposit, getOrCreateAccount, saveAccountIfNew, saveCertRecord - Clarify certDeposits parameter documentation in store interface Signed-off-by: Chris Gianelloni <[email protected]>