Dealership Integration

When a player purchases a vehicle, issue the key after the purchase and ownership transaction succeeds.
-- purchase validated, money removed and ownership row saved first
exports.nord_vehiclekeys:GiveKeys(source, plate)
When a dealership sells/transfers/removes a vehicle from a player, remove the old holder's key deliberately:
exports.nord_vehiclekeys:RemoveKeys(oldOwnerSource, plate)
If the new owner is online:
exports.nord_vehiclekeys:GiveKeys(newOwnerSource, plate)
This keeps physical key ownership explicit and avoids silent regeneration.