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.

packages/zappier-accounting-export/test/health.test.js

@@ -17,6 +17,8 @@ test('accounting-export health', async () => {
   try {
     const r = await fetch(`http://127.0.0.1:${port}/health`);
     assert.equal((await r.json()).role, 'zappier-accounting-export');
+    const home = await fetch(`http://127.0.0.1:${port}/`);
+    assert.equal(home.status, 200);
   } finally {
     child.kill('SIGTERM');
   }