refactor: group uuid instead of index

internal/model/game/group.go

@@ -105,10 +105,10 @@ func (t Tech) String() string {
 }
 
 type ShipGroup struct {
-	Index         uint       `json:"index"`              // FIXME: use UUID for Group Index (ordered)
-	OwnerID       uuid.UUID  `json:"ownerId"`            // Race link
-	TypeID        uuid.UUID  `json:"typeId"`             // ShipType link
-	FleetID       *uuid.UUID `json:"fleetId,omitempty"`  // Fleet link
+	ID            uuid.UUID  `json:"id"`
+	OwnerID       uuid.UUID  `json:"ownerId"`            // Race reference
+	TypeID        uuid.UUID  `json:"typeId"`             // ShipType reference
+	FleetID       *uuid.UUID `json:"fleetId,omitempty"`  // Fleet reference
 	Number        uint       `json:"number"`             // Number (quantity) ships of specific ShipType
 	CargoType     *CargoType `json:"loadType,omitempty"` //
 	Load          Float      `json:"load"`               // Cargo loaded - "Масса груза"

internal/model/game/group_test.go

@@ -162,7 +162,7 @@ func TestShipGroupEqual(t *testing.T) {
 	mat := game.CargoMaterial
 	cap := game.CargoCapital
 	left := &game.ShipGroup{
-		Index:  1,
+		ID:     uuid.New(),
 		Number: 1,
 
 		OwnerID:   uuid.New(),
@@ -241,7 +241,7 @@ func TestShipGroupEqual(t *testing.T) {
 	// non-essential properties
 	right = *left
 
-	left.Index = 2
+	left.ID = uuid.New()
 	assert.True(t, left.Equal(right))
 
 	// dirty hack to equalize loads