Extend the real-engine program to more services

[NitinKumar004]

Goal: the opt-in real-engine program (config.With*Engine) makes a data plane actually execute the workload instead of emulating only the control surface. Today it covers 6 categories — Compute, Container, Database, Cache, Function/serverless, Storage. Extend it so more services run for real.

Candidate next engines:

• Message queues / notifications (SQS/SNS/PubSub) — real delivery, ordering, FIFO, DLQ semantics
• Streams (Kinesis) — real record ingestion/ordering/shard iterators
• Step Functions — real ASL state-machine execution (see AWS: Step Functions ASL execution + KMS↔Secrets/SSM real encryption #581)
• Search (OpenSearch / AI Search) — real index + query
• DNS (Route53) — real resolution
• API Gateway — real route match + backend invoke

Each engine stays opt-in (wire nothing → pure in-memory control surface, unchanged); wiring config.WithEngine makes that service's data plane real. Grow the list over time.