chore(registry): removes unused method

core/services/workflows/syncer/engine_registry.go

@@ -48,14 +48,6 @@ func (r *engineRegistry) IsRunning(id string) bool {
 	return engine.Ready() == nil
 }
 
-// Exists checks if an engine exists in the registry.
-func (r *engineRegistry) Exists(id string) bool {
-	r.mu.RLock()
-	defer r.mu.RUnlock()
-	_, found := r.engines[id]
-	return found
-}
-
 // Pop removes an engine from the registry and returns the engine if found.
 func (r *engineRegistry) Pop(id string) (*workflows.Engine, error) {
 	r.mu.Lock()