Arcana maintenance backend behaviour。
默认实现调用 Arcana.Maintenance;测试可替换为 mock backend。
Arcana.Maintenance
@callback detect_communities( module(), keyword() ) :: {:ok, map()} | {:error, term()}
@callback embed_entities( module(), keyword() ) :: {:ok, map()} | {:error, term()}
@callback rebuild_graph( module(), keyword() ) :: {:ok, map()} | {:error, term()}
@callback reembed( module(), keyword() ) :: {:ok, map()} | {:error, term()}
@callback summarize_communities( module(), keyword() ) :: {:ok, map()} | {:error, term()}