Provider: AWS Route 53

[Selcukatli]

Add AWS Route 53 as a DNS provider so namecom-cli's agent-friendly surface (--json, idempotent records set, commands introspection) works for AWS Route 53-hosted domains.

Why: AI agents can automate almost all of Resend/Clerk/Cloudflare onboarding except DNS. This closes that gap for AWS Route 53 users.

Where to start:

• The provider contract is the method shape of NameClient in src/client.js (listDomains, listRecords, getRecord, createRecord, updateRecord, deleteRecord).
• See CONTRIBUTING.md → Adding a provider.
• Comment here before starting — we'll extract the shared provider interface together as the second provider lands (so the abstraction stays honest).

Done when:

• Provider implements the contract against the AWS Route 53 API
• Auth wired through src/auth.js (keychain/env, no global exports)
• --json output consistent with Name.com
• Unit tests for any pure mapping logic (AWS Route 53 record model → common shape)
• README/skill note that AWS Route 53 is supported

API reference: https://docs.aws.amazon.com/Route53/latest/APIReference/API_ChangeResourceRecordSets.html