Add LabelNameValues method to LabelState, returning composite "name:value" strings for all labels with non-empty values. Add LabelValues and NegatedLabelValues fields to IssueSearchOptions and PullSearchOptions. Change NegatedAuthorDid from a single string to NegatedAuthorDids []string to support excluding multiple authors. Update both issue and pull indexers: bump mapping version to 3, add label_values keyword field, populate it via LabelNameValues, and add search clauses for the new fields. Signed-off-by: Thomas Karpiniec <tom.karpiniec@outlook.com>