Disallow the client from tracking accounts with similar `AccountId` prefixes

To maintain a one-to-many relationship between accounts and addresses/tags, the same address (and the resulting tag) should always map to a single account in the client.

To do this, we need to prevent adding the account with the same prefix to the client.

See https://github.com/0xMiden/miden-client/issues/1260#issuecomment-3282601430 and https://github.com/0xMiden/miden-client/issues/1260#issuecomment-3270169022