99058350c0
Adds 55 new tests across three files in a new Stress/ directory,
covering concurrent pub/sub SubList thread safety, slow consumer
detection under real NatsServer connections, and clustered JetStream
operations under concurrency. All tests carry [Trait("Category",
"Stress")] for selective execution. Go ref: norace_1_test.go,
norace_2_test.go.