Summary

• When a bounded streaming input (e.g. CTE with LIMIT) finished before any periodic watermark fired, AggregatingTransform::prepare() would close the output without finalizing buffered aggregation state — resulting in silently empty results.
• Fix: inject a synthetic watermark when the input finishes with accumulated but un-finalized rows, triggering the existing finalization path.
• Added regression test 98468_streaming_cte_limit_aggregation covering CTE streaming + count(), GROUP BY, subquery, and non-aggregate passthrough.