Function evaluate 

pub async fn evaluate(
    provider: &dyn ReleaseProvider,
    current: &Version,
    policy: UpdatePolicy,
    interval: Duration,
    state_path: &Path,
    now_unix: i64,
) -> Result<PolicyDecision>

Run the synchronous, throttled pre-run update check.

Returns PolicyDecision::NoAction immediately when policy is UpdatePolicy::Disabled (zero overhead) or when the last check was within interval of now_unix. Otherwise queries provider, records the check in the state file regardless of outcome (so the throttle advances), and reports whether a newer release is available.

now_unix is the current Unix timestamp in seconds, injected so the throttle is deterministic in tests.

Errors

Propagates a provider error from ReleaseProvider::latest_release.