ragleap-graph (Java) v0.4.0 release notes

Community detection in Java: Communities (deterministic Louvain, compared with the real Python code), GraphIndex detectCommunities, refreshCommunities and findCommunities (checked once on a live Neo4j 5.26), and an opt-in community lookup in GraphRetriever (includeCommunities, default off). Release build: 174 tests, 0 failures, 40 skipped. No claim that communities improve answers. Depends on ragleap-rag 0.13.0.