Document Kafka listener consumer settings by endpoint mode

[jeremydmiller]

Summary

• Added a new "Listener Consumer Settings" section (badged to 5.16) to the Kafka transport docs
• Documents how EndpointMode.Durable vs non-durable modes affect EnableAutoCommit and EnableAutoOffsetStore on the Kafka ConsumerConfig
• Explains when KafkaListener commits offsets (successful processing, poison pills, DLQ routing)
• Provides recommended configuration examples for at-least-once, at-most-once, and inline processing use cases

Test plan

• Verify docs render correctly with npm run docs

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