refactor(session): add registry to manage SSH sessions

- Implement thread-safe session registry with sync.RWMutex
- Add Registry interface for session management operations
- Support Get, Register, Update, and Remove session operations
- Enable dynamic slug updates for existing sessions

session/slug/slug.go

@@ -1,32 +1,24 @@
 package slug
 
-import "sync"
-
 type Manager interface {
 	Get() string
 	Set(slug string)
 }
 
 type manager struct {
-	slug   string
-	slugMu sync.RWMutex
+	slug string
 }
 
 func NewManager() Manager {
 	return &manager{
-		slug:   "",
-		slugMu: sync.RWMutex{},
+		slug: "",
 	}
 }
 
 func (s *manager) Get() string {
-	s.slugMu.RLock()
-	defer s.slugMu.RUnlock()
 	return s.slug
 }
 
 func (s *manager) Set(slug string) {
-	s.slugMu.Lock()
 	s.slug = slug
-	s.slugMu.Unlock()
 }