removed device_id from all entities except car. Replaced with car_id . Car -> device_id

server/internal/storage/postgres/migrations/015_driver_car_id.sql

@@ -0,0 +1,8 @@
+-- 015_driver_car_id.sql — move device_id to cars table and use car_id in lobby_drivers
+--
+-- Represents the currently selected physical ESP32 DEVICE_ID (0..127) for a car.
+-- And represents the currently selected car ID for a driver in lobby_drivers.
+
+ALTER TABLE cars ADD COLUMN IF NOT EXISTS device_id INT;
+ALTER TABLE lobby_drivers ADD COLUMN IF NOT EXISTS car_id TEXT;
+ALTER TABLE lobby_drivers DROP COLUMN IF EXISTS device_id;