feat(enakgame): spin as an EnakGame game; remove the old game flow

EnakGame phase 10 of docs/tasks-enakgame.md (EG-1001 to EG-1003).

Spin (EG-1001)
- PROBABILITY entries take an optional label (a wheel segment). The customer game
  list shows a PROBABILITY game's prizes (entry, label, amount, never weights), and
  completing returns the drawn prize, so the client can draw the wheel and stop it
  on the server's draw.
- docs/enakgame-spin.md: the admin steps to set up spin per organization (no
  seeder) and the customer app flow. An HTTP test plays it end to end.

Old game flow removed (EG-1002)
- Routes POST /customer/spin, GET /customer/games, GET /customer/ferris-wheel, and
  admin /marketing/games, /marketing/game-prizes, /marketing/rewards, with their
  handlers, services, processors, repositories, validators, models, contracts,
  mappers and tests (GamePlayProcessor, SpinGameService, rewards, ...). This also
  closes RFC §15 findings 1 and 2 (double charge, spinning another org's game).
- Tables games, game_prizes, game_plays and rewards stay for ledger history.
  entities.StringSlice moves to its own file; the omset tracker (unrouted) keeps
  game_id but no longer embeds the old game response.

games.is_active dropped (EG-1003)
- Migration 000115; nothing reads metadata.coin_cost any more.

The EnakPoint integration docs now point at /customer/enakgame. The Postgres tests
were not run: no test database here. Migration 000115 has not been run anywhere.
The customer app must stop calling the removed endpoints before this is deployed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/entities/game.go

@@ -16,11 +16,12 @@ const (
 )
 
 type Game struct {
-	ID       uuid.UUID `gorm:"type:uuid;primary_key;default:gen_random_uuid()" json:"id"`
-	Name     string    `gorm:"type:varchar(255);not null" json:"name" validate:"required"`
-	Type     GameType  `gorm:"type:varchar(50);not null" json:"type" validate:"required,oneof=SPIN RAFFLE MINIGAME"`
-	IsActive bool      `gorm:"default:true" json:"is_active"`
-	Metadata Metadata  `gorm:"type:jsonb;default:'{}'" json:"metadata"`
+	ID   uuid.UUID `gorm:"type:uuid;primary_key;default:gen_random_uuid()" json:"id"`
+	Name string    `gorm:"type:varchar(255);not null" json:"name" validate:"required"`
+	Type GameType  `gorm:"type:varchar(50);not null" json:"type" validate:"required,oneof=SPIN RAFFLE MINIGAME"`
+	// The old games' settings. Nothing reads it any more; their coin_cost became
+	// entry_cost (migration 000103).
+	Metadata Metadata `gorm:"type:jsonb;default:'{}'" json:"metadata"`
 
 	// EnakGame (docs/rfc-enakgame.md §5.1). Only an ARCHIVED game, which every old game
 	// is, may lack an organization and a slug.
@@ -39,9 +40,6 @@ type Game struct {
 
 	CreatedAt time.Time `gorm:"autoCreateTime" json:"created_at"`
 	UpdatedAt time.Time `gorm:"autoUpdateTime" json:"updated_at"`
-
-	Prizes []GamePrize `gorm:"foreignKey:GameID" json:"prizes,omitempty"`
-	Plays  []GamePlay  `gorm:"foreignKey:GameID" json:"plays,omitempty"`
 }
 
 func (g *Game) BeforeCreate(tx *gorm.DB) error {