Tools declaring profile >= 24.2 with a legacy 'doi:'-prefixed citation
crashed during loading on 26.1 and were silently dropped from the toolbox.
- Normalize the legacy 'doi:' prefix to a bare DOI in the shared Citation
model so these citations load and resolve correctly downstream.
- Only fail tool loading fatally for profile >= 26.1; older profiles skip
the offending citation and log a warning instead of silently dropping the
whole tool.
- Add a CitationsDoiInvalid linter so authors are told to drop the prefix.