feat(enakgame): game sessions, rewards, vouchers, budgets and events

EnakGame phases 1-8 of docs/tasks-enakgame.md (EG-101 to EG-803), built on the
existing EnakPoint/EnakCoin wallet (docs/rfc-enakgame.md).

Foundation (phase 1)
- Migrations 000103-000106: games extended with organization, slug, status,
  entry cost and result rules, old games archived (not deleted); budgets,
  versioned reward configs, sessions and session rewards; the ledger types
  GAME_SPEND_REFUND, GAME_REWARD and REWARD_REDEEM_REFUND; audit_logs.
- AuditLogger writes in the caller's transaction only.
- enakgame.limit.user_daily and global_daily organization settings.

Games and sessions (phases 2-4)
- Admin /marketing/enakgame: games, reward config versions (immutable but for
  status, one ACTIVE per game), budgets with non-overlapping global periods and
  a daily job opening the next month.
- Customer /customer/enakgame: start (Idempotency-Key, entry cost and config
  frozen on the session), complete (result validation, reward engine, max_reward
  cap, daily limits via game_reward_counters, one GAME_REWARD per budget),
  automatic refunds for system errors and deactivated games, and a session job.
- Reward engine: FIXED, SCORE_BASED, OUTCOME_BASED, PROBABILITY (crypto/rand),
  rounded down.

Vouchers and budgets (phases 5-6)
- Migration 000108 and 000107: vouchers, codes, redemptions, cost attribution;
  Economy Guard counters.
- STATIC and CODE_POOL redemption in one transaction with the REDEEM PIN action;
  realized cost traced through the lots to the budget that paid the reward.
- Budget metrics: realized cost, forecast, exposure and status. Migrations
  000109-000110 add the wallet_lots indexes they need, built CONCURRENTLY.

Events (phase 7)
- Migration 000111: game events, each with its own EVENT budget. Event extras
  stack per PRD §16 defaults, with event and per-customer limits.

External vouchers (phase 8)
- VoucherProvider contract, two-step PENDING redemption and a recovery job,
  tested with a fake provider. No provider adapter is registered yet, so
  EXTERNAL vouchers stay out of the catalog.

Not yet decided before release: reward rounding, event stacking, budget
exhaustion policy and thresholds (RFC §19.2). Migrations 000103-000111 have
not been run on any shared database.

Also fixes a leftover PAYMENT filter in a wallet test and a data race in a
test PIN fake.

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

internal/processor/audit_logger_test.go

@@ -0,0 +1,129 @@
+package processor
+
+import (
+	"context"
+	"os"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gorm.io/driver/postgres"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+
+	"apskel-pos-be/internal/constants"
+	"apskel-pos-be/internal/entities"
+	"apskel-pos-be/internal/repository"
+)
+
+type auditRepoFake struct{ rows []entities.AuditLog }
+
+func (f *auditRepoFake) Insert(_ context.Context, e *entities.AuditLog) error {
+	f.rows = append(f.rows, *e)
+	return nil
+}
+
+func (f *auditRepoFake) ListByEntity(context.Context, uuid.UUID, string, uuid.UUID, int) ([]entities.AuditLog, error) {
+	return f.rows, nil
+}
+
+func validAuditEntry() AuditEntry {
+	return AuditEntry{
+		OrganizationID: uuid.New(),
+		ActorType:      constants.AuditActorUser,
+		ActorID:        ptr(uuid.New()),
+		EntityType:     constants.AuditEntityGame,
+		EntityID:       uuid.New(),
+		Action:         "STATUS_CHANGED",
+		Before:         map[string]string{"status": "DRAFT"},
+		After:          map[string]string{"status": "ACTIVE"},
+		Source:         constants.AuditSourceAdminAPI,
+	}
+}
+
+func TestAuditLogger_RecordsSnapshotsAsJSON(t *testing.T) {
+	repo := &auditRepoFake{}
+	l := NewAuditLogger(repo)
+	require.NoError(t, l.Record(context.Background(), validAuditEntry()))
+
+	created := validAuditEntry()
+	created.ActorType, created.ActorID = constants.AuditActorSystem, nil
+	var nothing *entities.Game
+	created.Before = nothing
+	require.NoError(t, l.Record(context.Background(), created))
+
+	require.Len(t, repo.rows, 2)
+	assert.JSONEq(t, `{"status": "DRAFT"}`, string(repo.rows[0].Before))
+	assert.JSONEq(t, `{"status": "ACTIVE"}`, string(repo.rows[0].After))
+	assert.Nil(t, repo.rows[1].Before, "a nil pointer is stored as NULL, not as JSON null")
+}
+
+func TestAuditLogger_RejectsIncompleteEntries(t *testing.T) {
+	for name, mutate := range map[string]func(*AuditEntry){
+		"no organization":    func(e *AuditEntry) { e.OrganizationID = uuid.Nil },
+		"unknown actor type": func(e *AuditEntry) { e.ActorType = "ROBOT" },
+		"USER without actor": func(e *AuditEntry) { e.ActorID = nil },
+		"no entity type":     func(e *AuditEntry) { e.EntityType = " " },
+		"no entity id":       func(e *AuditEntry) { e.EntityID = uuid.Nil },
+		"no action":          func(e *AuditEntry) { e.Action = "" },
+		"no source":          func(e *AuditEntry) { e.Source = "" },
+		"unmarshallable":     func(e *AuditEntry) { e.After = func() {} },
+	} {
+		repo := &auditRepoFake{}
+		e := validAuditEntry()
+		mutate(&e)
+		err := NewAuditLogger(repo).Record(context.Background(), e)
+		assert.ErrorIs(t, err, ErrInvalidAuditEntry, name)
+		assert.Empty(t, repo.rows, name)
+	}
+}
+
+// An audit row commits and rolls back with the change it records. Needs
+// TEST_DATABASE_URL; see internal/repository/wallet_repository_test.go.
+func TestAuditLogger_AgainstPostgres(t *testing.T) {
+	dsn := os.Getenv("TEST_DATABASE_URL")
+	if dsn == "" {
+		t.Skip("TEST_DATABASE_URL not set")
+	}
+	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{Logger: logger.Default.LogMode(logger.Silent)})
+	require.NoError(t, err)
+	org := uuid.New()
+	t.Cleanup(func() { db.Exec(`DELETE FROM audit_logs WHERE organization_id = ?`, org) })
+
+	repo := repository.NewAuditLogRepository(db)
+	l := NewAuditLogger(repo)
+	txm := repository.NewTxManager(db)
+	entry := func(entityID uuid.UUID) AuditEntry {
+		e := validAuditEntry()
+		e.OrganizationID, e.EntityID, e.Reason = org, entityID, ptr("promo")
+		return e
+	}
+	ctx := context.Background()
+
+	committed, rolledBack := uuid.New(), uuid.New()
+	require.NoError(t, txm.WithTransaction(ctx, func(ctx context.Context) error {
+		return l.Record(ctx, entry(committed))
+	}))
+	failure := assert.AnError
+	err = txm.WithTransaction(ctx, func(ctx context.Context) error {
+		require.NoError(t, l.Record(ctx, entry(rolledBack)))
+		return failure
+	})
+	require.ErrorIs(t, err, failure)
+
+	rows, err := repo.ListByEntity(ctx, org, constants.AuditEntityGame, committed, 10)
+	require.NoError(t, err)
+	require.Len(t, rows, 1)
+	assert.Equal(t, "STATUS_CHANGED", rows[0].Action)
+	assert.JSONEq(t, `{"status": "DRAFT"}`, string(rows[0].Before))
+	assert.JSONEq(t, `{"status": "ACTIVE"}`, string(rows[0].After))
+	assert.Equal(t, "promo", *rows[0].Reason)
+	assert.False(t, rows[0].CreatedAt.IsZero())
+
+	rows, err = repo.ListByEntity(ctx, org, constants.AuditEntityGame, rolledBack, 10)
+	require.NoError(t, err)
+	assert.Empty(t, rows, "a rolled back change leaves no audit row")
+
+	assert.ErrorIs(t, l.Record(ctx, entry(uuid.New())), repository.ErrAuditTxRequired)
+}