feat(billing): rating engine, fechamento de periodo, dashboard platform (fase 22)

Fecha a orquestracao de Billing (agente.md secao 120-139) sobre o schema/
RatingEngine puro ja existentes: escritores do ledger UsageEvent
(CALL_SECONDS no CDR, ACTIVE_DAY via sweep diario), closeBillingPeriod/
reopenBillingPeriod (fechamento imutavel com audit trail), e os
controllers de price books/rate decks/plan versions/subscriptions/
periods/statements. Corrige 2 bugs reais de RLS achados no teste ponta a
ponta (reopen sem tenant context, subscriptions sem withTenantContext) e
adiciona teste unitario do RatingEngine (17 casos).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EWHKmcVJtstQFErbZ1AanY

packages/billing/src/index.ts

@@ -0,0 +1,11 @@
+export type { RateDeckEntryLike, PriceBookItemLike, CallRatingResult } from "./types";
+export {
+  longestPrefixMatch,
+  resolvePriceBookItem,
+  rateCallByDestination,
+  rateCallFlatFallback,
+  rateGenericUsage,
+  rateActiveDaysProrated,
+  rateTranscriptionSeconds,
+  rateRecordingBytes,
+} from "./rating-engine";