Track review-stack AWS demo integration checkpoint #461

Track a draft integration checkpoint assembled from the existing AWS demo feature work and its review PRs. This is extraction/restacking, not a new SDK or TS redesign.

Review order: #275, #406, #407, #409, #414, #422, #439, then standalone prototype #454. Existing #401/#389 and explicitly identified RC-only demo extractions join the integration branch. #453 is excluded. Existing #431 remains available; this task does not authorize its closure or branch deletion.

Record exact constituent and integration heads, required merge resolutions, current focused/combined checks and all remaining CI/qualification failures. Keep the integration PR draft and do not merge it into main. TS compatibility is a separate checkpoint and must not block this framework draft.

No deployment, live infrastructure/input switch, cloud acceptance, recovery-ref deletion or old-RC retirement.