Add NATS account-balance SoT and statement review for customers, CS, and sales

Internal billing now uses verae.billing.* request-reply and pubs. zappier-account-balance tracks prepaid, credits, usage, and payments. Portal, admin, CS, and sales all review the same statement. Independent Forgejo repos stay split via push-module-repos.

docs/sphinx/modules/zappier/portal.md

@@ -2,7 +2,7 @@
 
 **Package:** `zappier`  
 **Source:** `packages/zappier/src/portal.ts`  
-**Lines:** 285
+**Lines:** 321
 
 ## What this module is
 
@@ -48,10 +48,13 @@ Implementation module in `zappier`. The tables below are extracted from the sour
 - `./invoicing`
 - `./pricing`
 - `./usage`
+- `./credits`
+- `./statement`
+- `./billing-nats`
 
 ## Call graph (identifiers invoked)
 
-`now`, `reload`, `customer`, `publicProfile`, `sessionAuth`, `header`, `startsWith`, `slice`, `get`, `list`, `find`, `status`, `json`, `next`, `save`, `portalRouter`, `post`, `trim`, `test`, `hashPassword`, `findByEmail`, `randomBytes`, `toString`, `create`, `verifyPassword`, `verifyTotp`, `use`, `delete`, `setUTCDate`, `setUTCHours`, `summaryFor`, `tiers`, `applyMonthlyCredit`, `rateCard`, `type`, `send`, `renderInvoiceHtml`, `async`, `generateTotpSecret`, `totpUri`, `qr`, `isInteger`, `put`
+`now`, `reload`, `customer`, `publicProfile`, `sessionAuth`, `header`, `startsWith`, `slice`, `get`, `list`, `find`, `status`, `json`, `next`, `save`, `portalRouter`, `post`, `trim`, `test`, `hashPassword`, `findByEmail`, `randomBytes`, `toString`, `create`, `verifyPassword`, `verifyTotp`, `use`, `delete`, `setUTCDate`, `setUTCHours`, `summaryFor`, `tiers`, `applyMonthlyCredit`, `rateCard`, `async`, `natsStatement`, `composeStatement`, `listFor`, `type`, `send`, `renderInvoiceHtml`, `generateTotpSecret`, `totpUri`, `qr`, `isInteger`, `natsPublish`, `natsAdjust`, `put`
 
 Each identifier is a call site in this file. Follow the import list to see the defining module; open that module’s MD for parameter and return types.