docs: list compat test make targets (#1914)

Author: earayu

Makefile

@@ -48,6 +48,9 @@ help:
 	@printf "  make test-integration     Run integration tests\n"
 	@printf "  make test-e2e             Run pytest-based residual E2E tests\n"
 	@printf "  make test-e2e-perf        Run pytest-based E2E performance tests\n"
+	@printf "  make test-compat-graph    Run graph-store compatibility tests (PG + optional Neo4j/Nebula)\n"
+	@printf "  make test-compat-vector   Run vector-store compatibility tests (Qdrant + pgvector)\n"
+	@printf "  make test-compat-all      Run graph + vector compatibility tests\n"
 	@printf "  make test-http-bootstrap  Prepare HTTP E2E bootstrap state\n"
 	@printf "  make test-http-smoke      Run HTTP smoke suite against an existing target\n"
 	@printf "  make test-http-full       Run full HTTP suite against an existing target\n"