feat: caster implementation switched to actual shell interpreter

internal/errors/errors.go

@@ -9,4 +9,5 @@ var (
 	ErrNoDBProvided     = fmt.Errorf("no db provided")
 	ErrNotFound         = fmt.Errorf("not found")
 	ErrEmptyQuery       = fmt.Errorf("empty search query")
+	ErrTemplateFailed   = fmt.Errorf("failed to execute spell template")
 )