test(log): add comprehensive benchmarks

Adds a new benchmark_test.go file with comprehensive benchmarks for the logging library:

Serial benchmarks:
- Trace, Debug, Info, Notice, Warn, Error levels

Formatted logging:
- Debugf, Infof, Errorf variants

Parallel benchmarks:
- DebugParallel, InfoParallel, InfofParallel

Logger instance (namespaced):
- LoggerInfo, LoggerInfof, LoggerDebugParallel

Multiple clients/namespaces:
- MultipleClients, MultipleNamespaces

Message size comparison:
- Short, Medium, Long messages

Level filtering overhead:
- DebugFilteredByLevel

Also removes the duplicate BenchmarkDebugSerial from log_test.go and applies minor whitespace formatting fixes.

Fixes #6

log/log.go

@@ -99,7 +99,7 @@ func createLog(e Entry) {
 	namespacesMux.Lock()
 	namespaces[e.Namespace] = true
 	namespacesMux.Unlock()
-	
+
 	sliceTex.Lock()
 	for _, c := range clients {
 		func(c *Client, e Entry) {
@@ -126,7 +126,7 @@ func createLog(e Entry) {
 func GetNamespaces() []string {
 	namespacesMux.RLock()
 	defer namespacesMux.RUnlock()
-	
+
 	result := make([]string, 0, len(namespaces))
 	for ns := range namespaces {
 		result = append(result, ns)