- Convert TestListDevices from map to handlers.DeviceListResponse
- Convert TestUpdateDevice to use handlers.DeviceUpdateRequest
- Add database verification after device update:
* Query DB to verify sync_enabled, sync_frequency actually updated
* Ensures data integrity - API says success, DB confirms it
- Impact: Compile-time safety for device endpoints, data integrity verification
Pattern: Replaces map[string]interface{} with type-safe structs,
ensures API changes caught at compile time, operations actually persist.