feat: implement cmd management for targets, LUNs, and TPGTs (fixes #36)

- Fix target delete URL path mismatch (/targets/ -> /target/)
- Implement target create/delete server handlers with proper validation
- Add DeleteTarget method with force flag and mutex locking to SCSITargetService
- Implement full LU management: create/list/delete through CLI, client, and server
- Add TPGT list command to show target portal group tags
- Add unit tests for target/LU router handlers and SCSI service

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/scsi/scsilumap.go

@@ -130,6 +130,13 @@ func DelLUNMapping(m LUNMapping) {
 	delete(globalSCSILUMap.TargetsLUNMap[m.TargetName], m.LUN)
 }
 
+// DelTargetLUNMap removes the entire LUN map for a target.
+func DelTargetLUNMap(targetName string) {
+	globalSCSILUMap.mutex.Lock()
+	defer globalSCSILUMap.mutex.Unlock()
+	delete(globalSCSILUMap.TargetsLUNMap, targetName)
+}
+
 func InitSCSILUMap(config *config.Config) error {
 	for _, bs := range config.Storages {
 		if err := AddBackendStorage(bs); err != nil {