Add protocol performance benchmark tool

- Add cmd/protocolperf for comparing Direct Engine, TCP, and HTTP/AuthZen performance
- Add Config.Engine field to server package for engine injection (enables benchmarking)
- Add protocolperf and protocolperf-quick Makefile targets
- Add docs/PROTOCOL_PERFORMANCE.md with usage and interpretation guide

The benchmark uses library calls exclusively to eliminate external binary overhead,
providing accurate measurements of protocol overhead vs direct engine access.

Author: leifj

Makefile

@@ -1,4 +1,4 @@
-.PHONY: all build test test-verbose coverage clean fmt vet lint help bench bench-long perftest perftest-sizes perftest-large indexperf indexperf-large
+.PHONY: all build test test-verbose coverage clean fmt vet lint help bench bench-long perftest perftest-sizes perftest-large indexperf indexperf-large protocolperf protocolperf-quick
 
 # Go parameters
 GOCMD=go
@@ -116,6 +116,14 @@ indexperf-large: ## Compare indexed vs non-indexed with large ruleset (50k rules
 	@echo "Running index performance comparison (large)..."
 	$(GOCMD) run cmd/indexperf/main.go -rules 50000 -queries 5000 -tags 20 -stats
 
+protocolperf: ## Compare Direct vs TCP vs HTTP/AuthZen performance
+	@echo "Running protocol performance comparison..."
+	$(GOCMD) run cmd/protocolperf/main.go -rules 1000 -queries 10000
+
+protocolperf-concurrent: ## Compare protocols with concurrent clients
+	@echo "Running protocol performance comparison (concurrent)..."
+	$(GOCMD) run cmd/protocolperf/main.go -rules 1000 -queries 10000 -concurrent 4
+
 deps: ## Download dependencies
 	@echo "Downloading dependencies..."
 	$(GOMOD) download