v0.2.5

Added

• Graph communities + global queries (P3-5). Opt-in GraphRAG-style
  sensemaking: deterministic pure-Go Louvain detection over the ontology
  graph (hierarchical levels, no CGO), LLM-generated community summaries
  cached by member hash (unchanged communities cost nothing on recompiles),
  and a global query mode that map-reduces over summaries with
  community-level citations: wiki_graph_query with mode: "global".
  Enable with ontology.communities.enabled: true (default off — indexing
  cost is one Louvain run plus roughly members/10 cheap-model calls on first
  enable; global queries cost 1 + K calls). Community markdown lands in
  wiki/communities/.