test(simulation): map-agnostic invariant tests, 36 invariants (#508)

Adds test_world::invariants with 29 world-query invariants (structural,
perception, population, simulation) and 7 system-execution tests. All
invariants are gated behind the gauntlet feature and run against the
fully-initialized gauntlet world. Documents StableId ranges through
Sprint 14 rooms.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/Cargo.lock

@@ -1092,7 +1092,7 @@ dependencies = [
 
 [[package]]
 name = "settled-reach-server"
-version = "0.1.12"
+version = "0.1.13"
 dependencies = [
  "bevy_app",
  "bevy_ecs",