- query_database gains a database: param targeting any named database: a
  config/database.yml key (resolved via the host app's configurations
  registry first, so Rails multi-DB apps get credential-resolved configs)
  or a full connection URL. Results report which database was queried;
  write guards apply to all databases.
- The gem now requires active_record itself — standalone processes (the
  MCP server) previously failed ASK_DATABASE_URL connections with
  'uninitialized constant ActiveRecord'.

130 tests, 0 failures; verified live: query_database(database: 'queue')
and 'cache' return Anywaye's multi-DB databases through the harness.