validateAnnotations function
Recursively validates annotation markers under referenceDir.
Checks remove, insert, replace, and partial block pairing. Drop markers, Mustache unwrap comments, and spacing groups are not structurally validated.
Marker syntax and error messages: annotation reference.
Returns a list of AnnotationIssue values. Each issue formats as
filePath:line:column: message via AnnotationIssue.toString.
Implementation
List<AnnotationIssue> validateAnnotations({required Directory referenceDir}) {
return AnnotationValidator().validateDirectory(referenceDir);
}