VSN-2629/ optimize driver search with batch fetching and fix vehicleName mapping
- Replace N individual HTTP calls per driver with batch pre-fetch in mapBatch() (vehicles, departments, sectors, agencies, fuel cards resolved once per page)
- Add getDepartmentNamesByIds / getSectorNamesByIds batch endpoints in AdminService
- Fix vehicleName always null in response by setting it alongside vehicle object
- Fix compilation errors: primitive long vs Long null comparison in stream filters
- Fix circuit service connection failure crashing the entire search request (wrap individual circuit calls in try-catch, degrade gracefully to empty list)