Add msk-operations skill for Amazon MSK Provisioned troubleshooting and review

Covers both ad-hoc MSK/Kafka-on-AWS troubleshooting (performance, consumer
lag, storage, TrafficShaping, unexpected broker restarts) and a structured
8-step operational review workflow that produces a per-cluster report.
Handles Standard and Express brokers with broker-type-aware metric lists,
severity-scored findings, and alarm-coverage checks. Uses only public AWS
APIs (kafka, cloudwatch, logs).