Merge pull request 'fix: use full Lock in State.Save() to prevent data race (closes #17)' (#20) from fix/state-save-data-race into main

Reviewed-on: #20

internal/state/state.go

@@ -156,8 +156,8 @@ func (s *State) Load() error {
 
 // Save writes the current state to disk atomically.
 func (s *State) Save() error {
-	s.mu.RLock()
+	s.mu.Lock()
-	defer s.mu.RUnlock()
+	defer s.mu.Unlock()
 
 	s.snapshot.LastUpdated = time.Now().UTC()