pg_clickhouse v0.10: Subquery pushdown and 1000x faster TPC-H queries

pg_clickhouse v0.10.0 achieves full query pushdown for 16 of 22 TPC-H benchmark queries, up from 12 in the previous version, with notable performance improvements including a 1000x speedup on query Q17 through subquery pushdown optimization. The update includes a rebuilt C driver, doubled aggregate function coverage, and concurrency bug fixes, leaving only 6 queries requiring further work on join tree traversal for anti/semi-joins. These improvements demonstrate significant performance gains for analytic workloads, with some queries now outperforming native PostgreSQL execution.