Lower end-to-end latency from beacon to query

We have shipped a major rework of the stream processing pipeline that turns raw beacon events into the metrics surface used by every Data query. Key changes:

1. Incremental event processing — partial view sessions are processed as they arrive instead of waiting for the full session to close, reducing the lag between a viewer’s activity and that activity appearing in queries.
2. Efficient deduplication — duplicate-event detection now scales with view volume rather than session length.
3. View finalization — a new finalization step marks views as complete and stable, letting the query layer skip in-flight sessions and produce more accurate counts.