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/upstream.md

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+# `zappier/upstream`
+
+**Package:** `zappier`  
+**Source:** `packages/zappier/src/upstream.ts`  
+**Lines:** 46
+
+## What this module is
+
+Implementation module in `zappier`. The tables below are extracted from the source (signatures + JSDoc).
+
+## Exports
+
+`UpstreamFetch`, `proxyVerae`
+
+## Types / interfaces / classes
+
+| Kind | Name |
+|------|------|
+| type | `UpstreamFetch` |
+
+## Functions
+
+| Name | Parameters | Param types (JSDoc) | Returns | Calls (same file / helpers) |
+|------|------------|---------------------|---------|-----------------------------|
+| `proxyVerae` | `req: Request,
+  res: Response,
+  pathname: string,
+  fetchImpl: UpstreamFetch = fetch,` | — | `unknown` | see Call graph |
+
+## What it imports / requires
+
+- `express`
+
+## Call graph (identifiers invoked)
+
+`proxyVerae`, `replace`, `entries`, `set`, `header`, `toUpperCase`, `stringify`, `fetchImpl`, `toString`, `text`, `parse`, `isArray`, `status`, `json`
+
+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.
+
+## Return values (how to read this)
+
+- HTTP route handlers return Express `res.json(...)` bodies (see route docs).
+- Zapier `perform` functions return a **single object** (creates) or an **array** (triggers/searches).
+- Pricing functions return integer **cents** on `Quote.totalCents`.
+