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/meter.md

@@ -2,7 +2,7 @@
 
 **Package:** `zappier`  
 **Source:** `packages/zappier/src/meter.ts`  
-**Lines:** 49
+**Lines:** 52
 
 ## What this module is
 
@@ -22,7 +22,8 @@ _None extracted._
 |------|------------|---------------------|---------|-----------------------------|
 | `meter` | `endpointId: string,
   repo: UsageRepo,
-  pricing: PricingContext,` | — | `unknown` | see Call graph |
+  pricing: PricingContext,
+  onRecord?: (entry: { customerId: string; endpointId: string; cents: number }` | — | `unknown` | see Call graph |
 
 ## Methods (class / object)