Add deterministic tie-break to repair suggestion ranking

[VPDPersonal]

Summary

• Add a deterministic tie-break to the Smart-Fix candidate ranking in SerializeReferenceRepairSuggestions.Rank: after the descending-score sort, ties now break on the candidate's Type.FullName and then its assembly name (both Ordinal).
• Prevents the one-click repair suggestion from flipping between equally-scored same-named types (e.g. two Pistol classes in different namespaces) across domain reloads, which could otherwise re-point a reference to the wrong type.

Notes for review

• The previous sort keyed only on the discrete float Score with an unstable List.Sort, so the winner depended on TypeCache ordering. The new comparator is total and stable across reloads. No behavioural change for the common single-best-candidate case.

Linked issues

Refs #49 - addresses review finding #49 (comment)