Updated RecentReceiverSuggestionDto to use `init` properties,
adding immutability and a new `LastUsedAt` field. Refactored
ReadRecentReceiverSuggestionsQueryHandler to simplify query
logic, remove `IMapper` dependency, and improve determinism
in results. Introduced tie-breaking for duplicate timestamps
and optimized ordering by `LastUsedAt` and `EmailAddress`.
Removed redundant `Include` and mapping steps for clarity.