KIP-1091 — Improved Kafka Streams operator metrics

Discussion Kafka 4.0 StreamsMetrics

Introduces numeric JMX metrics for StreamThread state (CREATED/RUNNING/DEAD etc.) and KafkaStreams client state, plus a metrics.recording.level metric, enabling operator monitoring systems that require numeric gauges rather than string values. Existing Kafka Streams state metrics were string-typed and incompatible with KIP-714/KIP-1076 telemetry pipelines, making automated health alerting difficult.

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