Verify @activescott/auth-sms-aws end-to-end against a live AWS account

The AWS End User Messaging transport (`@activescott/auth-sms-aws`) is fully implemented with unit tests, docs, and example integration, but it has **not been verified against a live AWS account** — provisioning an origination identity requires SMS-sandbox exit and US A2P 10DLC registration, which the maintainer isn't taking on right now (the Twilio transport went through that process instead and shipped).

The code lives on the [`feat/sms-aws` branch](https://github.com/activescott/auth/tree/feat/sms-aws) with a draft PR ready to merge once verified. Snapshot also tagged `archive/sms-aws-v1`.

## Want to use AWS for SMS auth? Help verify it

If you have (or can set up) an AWS account with End User Messaging:

1. Check out the `feat/sms-aws` branch, `npm install && npm run build`.
2. Run the interactive setup: `cd examples/react-router-sms && ./scripts/setup-aws.mts` — it lists your origination identities (phone numbers, pools, sender IDs) and writes `.env` with `SMS_TRANSPORT=aws`.
3. `npm run dev --workspace=examples/react-router-sms` → http://localhost:5173/login → enter your real mobile → confirm the code arrives by text and signs you in.
4. Note anything that didn't work or needed changing (API surface drift in `@aws-sdk/client-pinpoint-sms-voice-v2`, IAM permissions the README missed, sandbox gotchas, RCS via pools).

Report results on the draft PR — a successful end-to-end run (and any fixes) is what's needed to merge and publish the package. US numbers need A2P 10DLC registration for carriers to deliver, same as any provider; the README on the branch covers the steps.