Release v0.3.71: Support arbitrary length MATCH chains with WITH pushdown

- _merge_with_prior_results reconstructs node-like dicts for new variables
- _extract_bound_ids handles flat SQL result format (var.id keys)
- Enables MATCH-WITH-MATCH-WITH-MATCH... patterns of any length
- New tests: TestArbitraryMatchChains in test_with_pushdown.py
- Verified on Databricks with LDBC SF10 (triple MATCH chain in 5.85s)