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

server/internal/catalog/catalog.go

@@ -247,6 +247,7 @@ type CreateCarOptions struct {
 	ColorHex   string
 	AvatarURL  string
 	Active     *bool // optional; defaults to true
+	DeviceID   *int
 }
 
 // Validate sanity-checks dimensions and required fields.
@@ -319,6 +320,7 @@ func (s *Service) CreateCar(ctx context.Context, opts CreateCarOptions) (CarMeta
 		ColorHex:   opts.ColorHex,
 		AvatarURL:  opts.AvatarURL,
 		Active:     active,
+		DeviceID:   opts.DeviceID,
 		CreatedMs:  now,
 		UpdatedMs:  now,
 	}
@@ -345,6 +347,7 @@ type UpdateCarOptions struct {
 	Motor      *MotorSpec
 	Battery    *BatterySpec
 	Drive      *Drivetrain
+	DeviceID   *int // double pointer or *int to clear / set? Let's use *int, but to allow setting to nil (e.g. if we pass -1 or use *int), wait, actually, we can support DeviceID **int or *int. Let's use *int for now or wait, if *int is nil, it means do not update. If they want to set to a device ID, they pass a pointer. Wait! What if they want to clear it? They can pass a pointer to a negative value like -1 or we can use a double pointer. Actually, in Go, *int is very simple. Let's make it *int. If we need to clear, we can pass a device ID of -1 and map it to nil. Let's check how the JSON schema handles it. Usually *int is sufficient. Wait, let's use *int.
 }
 
 // UpdateCar applies a partial update.
@@ -403,6 +406,13 @@ func (s *Service) UpdateCar(ctx context.Context, id string, opts UpdateCarOption
 	if opts.Drive != nil {
 		c.Drive = *opts.Drive
 	}
+	if opts.DeviceID != nil {
+		if *opts.DeviceID < 0 {
+			c.DeviceID = nil
+		} else {
+			c.DeviceID = opts.DeviceID
+		}
+	}
 	c.UpdatedMs = time.Now().UnixMilli()
 
 	if c.LengthMm < minCarLengthMm || c.LengthMm > maxCarLengthMm ||

server/internal/catalog/types.go

@@ -146,6 +146,7 @@ type CarMeta struct {
 	Motor    MotorSpec   `json:"motor"`
 	Battery  BatterySpec `json:"battery"`
 	Drive    Drivetrain  `json:"drive"`
+	DeviceID *int        `json:"device_id,omitempty"` // mapped physical ESP32 device ID
 
 	// Performance envelope.
 	TopSpeedMs float64 `json:"top_speed_ms"`