Feature Request: Add a unified account status API for connection and readiness checks

Applications using the Base Account SDK often need to determine whether an account is ready for interaction (configured, connected, correct network, and usable). Currently, developers must infer readiness by combining multiple calls and checks, which increases complexity.

Without a single source of truth for account status:
- Developers duplicate readiness logic across applications.
- UI may attempt account actions before the account is fully usable.
- Handling reconnects or partial configuration becomes error-prone.

### Describe the solution you'd like
Introduce a first-class `getAccountStatus()` API (or hook, where applicable) that returns a structured status object describing readiness, connectivity, network validity, and blocking reasons. The API should be synchronous where possible and reactive to underlying state changes.

The issue names no files, tests, or entry points. First map the existing account, connection, network, and readiness checks, then define the structured status and blocking reasons; done means one account-status API or hook reports readiness and reacts to underlying state changes.

Written by the indexing model from the issue text.