Account selection pops up even when no account exists for given blockchain

dApp detects presence of Beet. User initiates action via dApp UI. dApp makes transaction request. But Beet wallet has no account associated with the blockchain in question.

In such cases, I think the account selection dropdown list should not be displayed. Instead, display an error and perhaps a link to add an account for that blockchain.

Reproduce the flow from the dApp UI through the transaction request when Beet has no account for the requested blockchain. Inspect where the account-selection dropdown is triggered and verify the no-account path instead shows an error with an option to add an account. Done means the dropdown is not displayed in that case while normal account selection still works.

Written by the indexing model from the issue text.