perf(eap): Stream RowBinary INSERTs instead of buffering

[phacops]

RowBinary consumers now stream compressed INSERT bodies to ClickHouse as rows arrive, instead of accumulating the full uncompressed batch in Reduce before the write.

--use-row-binary (already on for EAP items) swaps Reduce → RowBinaryWriterStep for StreamingClickhouseWriter. Each message is LZ4-framed into ClickHouse-native 1 MiB blocks and pushed onto an in-flight INSERT … FORMAT RowBinary POST; uncompressed bytes are dropped in submit(). JSON storages stay on the buffered writer.

This is a re-land of #8001 with the two revert causes fixed:

• Concurrency. perf(eap): Stream RowBinary INSERTs to ClickHouse instead of buffering #8001 allowed one in-flight POST and rejected submits for the duration of insert_distributed_sync=1, which showed up as consumer pause time. This keeps clickhouse_concurrency slots and completes them in order so a later offset cannot commit before an earlier write.
• Partial-body retries. Closing the HTTP body is end-of-INSERT for ClickHouse. The live attempt streams as blocks are produced, but retries wait for body_complete so they replay the full compressed body, not a prefix. Abandoning a batch (rebalance / join timeout) aborts the HTTP task before dropping the sender, so a connection reset cannot land as a successful truncated write.

The first-attempt request timeout is request_ms + max_batch_time so the open connection covers accumulation plus the write; retries use plain request_ms. Peak writer memory for a batch of size B is the compressed retry buffer (~0.3×B) rather than the uncompressed Reduce accumulator.

Watch EAP canary RSS and pause time on deploy. The ClickHouse MEMORY_LIMIT_EXCEEDED / max_insert_block_size lever from #7939 is unchanged.

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