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/processor/reward_calculator.go

@@ -12,6 +12,7 @@ import (
 	"strings"
 
 	"apskel-pos-be/internal/constants"
+	"apskel-pos-be/internal/models"
 )
 
 var (
@@ -332,12 +333,18 @@ func (o outcomeBasedReward) Scale(rules json.RawMessage, multiplier int64) (json
 
 // PROBABILITY: {"table": [{"weight": 1, "amount": 1000}, {"weight": 999, "amount": 0}]}.
 // Weights are whole numbers, so no check depends on floating point (§8). The draw is
-// kept in the detail for audit.
+// kept in the detail for audit. An entry may carry a label, such as a spin wheel's
+// segment ("Zonk", "Jackpot"); the customer sees the entries and the one drawn, never
+// the weights.
 type probabilityReward struct{}
 
+// probabilityLabelLimit bounds a label's length.
+const probabilityLabelLimit = 100
+
 type probabilityEntry struct {
-	Weight *int64 `json:"weight"`
-	Amount *int64 `json:"amount"`
+	Weight *int64  `json:"weight"`
+	Amount *int64  `json:"amount"`
+	Label  *string `json:"label,omitempty"`
 }
 
 type probabilityRules struct {
@@ -363,6 +370,9 @@ func (probabilityReward) parse(rules json.RawMessage) (probabilityRules, int64,
 		if *e.Amount < 0 {
 			return r, 0, invalidRules("entry %d amount must be 0 or more", i+1)
 		}
+		if e.Label != nil && (strings.TrimSpace(*e.Label) == "" || len(*e.Label) > probabilityLabelLimit) {
+			return r, 0, invalidRules("entry %d label must not be empty, at most %d characters", i+1, probabilityLabelLimit)
+		}
 		total += *e.Weight
 		if total > rewardWeightLimit {
 			return r, 0, invalidRules("the weights add up to more than %d", rewardWeightLimit)
@@ -389,9 +399,13 @@ func (p probabilityReward) Calculate(rules json.RawMessage, _ SessionResult, rng
 	for i, e := range r.Table {
 		cumulative += *e.Weight
 		if roll < cumulative {
-			return *e.Amount, map[string]any{
+			detail := map[string]any{
 				"reward_type": constants.GameRewardTypeProbability, "roll": roll, "total_weight": total, "entry": i + 1,
-			}, nil
+			}
+			if e.Label != nil {
+				detail["label"] = *e.Label
+			}
+			return *e.Amount, detail, nil
 		}
 	}
 	return 0, nil, fmt.Errorf("draw %d is outside the total weight %d", roll, total)
@@ -410,3 +424,40 @@ func (p probabilityReward) Scale(rules json.RawMessage, multiplier int64) (json.
 	}
 	return marshalRules(r)
 }
+
+// probabilityPrizes lists the entries of PROBABILITY rules as the customer sees them:
+// in order, without their weights.
+func probabilityPrizes(rules json.RawMessage) ([]models.GamePrize, error) {
+	r, _, err := probabilityReward{}.parse(rules)
+	if err != nil {
+		return nil, err
+	}
+	prizes := make([]models.GamePrize, 0, len(r.Table))
+	for i, e := range r.Table {
+		prizes = append(prizes, models.GamePrize{Entry: i + 1, Label: e.Label, Amount: *e.Amount})
+	}
+	return prizes, nil
+}
+
+// drawnPrize is the entry a PROBABILITY reward drew, read back from its detail; nil
+// for another type or when nothing was drawn.
+func drawnPrize(rewardType string, base int64, detail map[string]any) *models.GamePrize {
+	if rewardType != constants.GameRewardTypeProbability {
+		return nil
+	}
+	// A number read back from JSON is a float64; one just drawn is an int.
+	var entry int
+	switch v := detail["entry"].(type) {
+	case int:
+		entry = v
+	case float64:
+		entry = int(v)
+	default:
+		return nil
+	}
+	prize := &models.GamePrize{Entry: entry, Amount: base}
+	if label, ok := detail["label"].(string); ok {
+		prize.Label = &label
+	}
+	return prize
+}