@rivetkit/effect: Client options for params, poolName and region #5922

@rivetkit/effect's Client covers most of what we need, but we still create a raw rivetkit/client for one service because the Effect client can't express three things the raw client can:

1. Connection params: our actors authenticate in createConnState from params (getOrCreate(key, { params })). Actor.Accessor.getOrCreate(key) takes only the key.
2. Pool: poolName (Rivet 3 pools). Client.Options is Pick<ClientConfigInput, "endpoint" | "token" | "namespace">.
3. Region: createInRegion on getOrCreate.

Proposal: widen Client.Options to include poolName (and other ClientConfigInput fields that don't conflict with the Effect logger), and let getOrCreate take an options object that is passed through to the raw getOrCreate, e.g. getOrCreate(key, { params, createInRegion }).

With this, a typed action call keeps the RivetError → typed-error decoding that makeRivetkitActionFailureClassifier already does, and we can delete our hand-written classifier.

Versions: @rivetkit/effect 2.3.25, rivetkit 2.3.25, Effect 4.0.1.