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_test.go

@@ -3,12 +3,14 @@ package processor
 import (
 	"encoding/json"
 	"math"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"apskel-pos-be/internal/constants"
+	"apskel-pos-be/internal/models"
 )
 
 // fixedRNG returns the given draws in turn.
@@ -179,3 +181,49 @@ func TestRewardCalculator_Scale(t *testing.T) {
 	require.NoError(t, err)
 	assert.EqualValues(t, math.MaxInt64/15_000*15_000/10_000, v)
 }
+
+// EG-1001: a spin wheel is a PROBABILITY game whose entries carry labels.
+func TestRewardCalculator_SpinPrizes(t *testing.T) {
+	rules := json.RawMessage(`{"table": [
+		{"weight": 50, "amount": 0, "label": "Zonk"},
+		{"weight": 45, "amount": 5, "label": "5 Coin"},
+		{"weight": 5, "amount": 50}]}`)
+	c, err := RewardCalculatorFor(constants.GameRewardTypeProbability)
+	require.NoError(t, err)
+	require.NoError(t, c.Validate(rules))
+
+	prizes, err := probabilityPrizes(rules)
+	require.NoError(t, err)
+	assert.Equal(t, []models.GamePrize{
+		{Entry: 1, Label: ptr("Zonk"), Amount: 0}, {Entry: 2, Label: ptr("5 Coin"), Amount: 5}, {Entry: 3, Amount: 50},
+	}, prizes, "no weights")
+
+	base, detail, err := c.Calculate(rules, SessionResult{}, &fixedRNG{draws: []int64{60}})
+	require.NoError(t, err)
+	assert.EqualValues(t, 5, base)
+	assert.Equal(t, &models.GamePrize{Entry: 2, Label: ptr("5 Coin"), Amount: 5}, drawnPrize(constants.GameRewardTypeProbability, base, detail))
+
+	// As read back from reward_breakdown.
+	stored, err := json.Marshal(detail)
+	require.NoError(t, err)
+	var back map[string]any
+	require.NoError(t, json.Unmarshal(stored, &back))
+	assert.Equal(t, &models.GamePrize{Entry: 2, Label: ptr("5 Coin"), Amount: 5}, drawnPrize(constants.GameRewardTypeProbability, base, back))
+
+	_, detail, err = c.Calculate(rules, SessionResult{}, &fixedRNG{draws: []int64{99}})
+	require.NoError(t, err)
+	assert.Equal(t, &models.GamePrize{Entry: 3, Amount: 50}, drawnPrize(constants.GameRewardTypeProbability, 50, detail), "no label")
+	assert.Nil(t, drawnPrize(constants.GameRewardTypeFixed, 5, map[string]any{"reward_type": "FIXED"}))
+	assert.Nil(t, drawnPrize(constants.GameRewardTypeProbability, 0, nil), "rejected: nothing drawn")
+
+	scaled, err := c.Scale(rules, 9_000)
+	require.NoError(t, err)
+	assert.Contains(t, string(scaled), `"label":"Zonk"`, "scaling keeps the labels")
+
+	for name, bad := range map[string]string{
+		"empty label":    `{"table": [{"weight": 1, "amount": 1, "label": " "}]}`,
+		"label too long": `{"table": [{"weight": 1, "amount": 1, "label": "` + strings.Repeat("x", 101) + `"}]}`,
+	} {
+		assert.ErrorIs(t, c.Validate(json.RawMessage(bad)), ErrInvalidRewardRules, name)
+	}
+}