Bench/Concurrent Publish Tool

[swarna1101]

mump2p bench --topic=test --workers=10 --rate=100

Spawn N concurrent goroutines publishing messages at configurable rate (messages/sec), support both HTTP and gRPC, and optionally subscribe in parallel to measure end-to-end delivery. Example: mump2p bench --topic=load-test --workers=50 --rate=1000 --duration=60s --grpc