feat: accounting module — schema, migration, Zod schemas, AR balance service
Phase 1 foundation:
- Migration 0047: all accounting tables (invoice, payment_application,
account_balance, account_code, journal_entry, billing_run), chart of
accounts seed, nextBillingDate on enrollment, accounting module config
- Drizzle schema file with all table definitions and type exports
- Zod validation schemas (invoice, payment, billing, reports)
- AccountBalanceService: materialized AR balance per account
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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