feat(enakgame): budget controller recommendations and analytics

EnakGame phase 9 of docs/tasks-enakgame.md (EG-901 to EG-903).

Budget Controller (EG-901, EG-902)
- GET /marketing/enakgame/budgets/:id/recommendation, GLOBAL budgets only: the
  multiplier (budget − realized) / (forecast − realized), within one step of 1,
  rounded down to two decimals, either way. Shows each game's new rules.
- POST .../recommendation/accept with the multiplier the admin saw: recomputed in the
  transaction, then one new ACTIVE version per game, the old one RETIRED, audited
  with source budget_controller and RECOMMENDATION_ACCEPTED on the budget.
- Migration 000112: base_config_id, multiplier and budget_id on
  game_reward_configs. Rules are always scaled from the admin's last version, so
  rounding does not compound and min/max are against what the admin set.
- Guardrails in game_budgets.thresholds: max_step_percent 10, min/max multiplier
  50-150%, cooldown_days 7 per organization. Provisional pending RFC §19.2 #4.
- RewardCalculator.Scale for the four reward types: amounts only, rounded down.

Analytics (EG-903)
- GET /marketing/enakgame/analytics/games and /analytics/economy over a range of
  Asia/Jakarta days (at most 366), from game_sessions and the wallet ledger.
- Migrations 000113 (game_sessions by organization and start) and 000114
  (wallet_transactions by organization and time, CONCURRENTLY).

The Postgres tests for accepting and analytics were not run: no test database here.
Migrations 000112-000114 have not been run anywhere.

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

internal/constants/enakgame.go

@@ -72,6 +72,9 @@ const (
 	AuditEntityVoucher          = "VOUCHER"
 )
 
+// audit_logs.action on a GAME_BUDGET whose recommendation was accepted.
+const AuditActionRecommendationAccepted = "RECOMMENDATION_ACCEPTED"
+
 // game_reward_counters.scope_type: what an Economy Guard counter counts for (§5.8).
 const (
 	GameRewardScopeUser   = "USER"
@@ -144,3 +147,32 @@ const (
 	GameEventStatusEnded     = "ENDED"
 	GameEventStatusCancelled = "CANCELLED"
 )
+
+// Budget Controller guardrails of a budget that sets none (PRD §31). Pending RFC
+// §19.2 #4.
+const (
+	// Percent a recommendation may move rewards by, either way.
+	GameBudgetMaxStepDefault = int64(10)
+	// Bounds of a game's multiplier, in percent of the configuration its admin wrote.
+	GameBudgetMinMultiplierDefault = int64(50)
+	GameBudgetMaxMultiplierDefault = int64(150)
+	// Days after an accepted recommendation before the next one, in the organization.
+	// The same as the forecast window, so the next one sees the effect of the last.
+	GameBudgetCooldownDaysDefault = int64(7)
+)
+
+// What a Budget Controller recommendation says (docs/rfc-enakgame.md §10). Only
+// RECOMMENDED can be accepted.
+const (
+	GameBudgetRecommended = "RECOMMENDED"
+	// The forecast meets the budget closely enough that rewards stay.
+	GameBudgetRecommendationNoChange = "NO_CHANGE"
+	// The last accepted recommendation of the organization is too recent.
+	GameBudgetRecommendationCooldown = "COOLDOWN"
+	// Every game is already at its min or max multiplier.
+	GameBudgetRecommendationAtLimit = "AT_LIMIT"
+	// No cost in the forecast window to extrapolate from.
+	GameBudgetRecommendationNoData = "INSUFFICIENT_DATA"
+	// The budget's period has not started or has no day left after today.
+	GameBudgetRecommendationOutOfPeriod = "OUT_OF_PERIOD"
+)