Audit whether agent/default/agentcore/cdk (hosting-stack.ts, sample-hosting.yml) is now dead code

if hosting is deployed exclusively through web/amplify/backend.ts going forward, agent/default/agentcore/cdk/lib/hosting-stack.ts and its supporting files may be unused. Worth confirming and removing if so, to avoid future confusion about which hosting path is authoritative.

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*Imported from `waltmayf/agentcore-amplify-fullstack`#39 — originally filed by @waltmayf on 2026-07-02. Migrated to open-source repo; cross-references updated post-import.*

Start with web/amplify/backend.ts, then inspect agent/default/agentcore/cdk/lib/hosting-stack.ts, sample-hosting.yml, and their supporting files. Search the repository for references to the CDK hosting path and confirm whether deployment uses only the Amplify backend; done means unused files are removed or their continued role is documented.

Written by the indexing model from the issue text.