Wire zappier-edge into the live stack and add billing department APIs

Fleet now spawns the real zappier and middleware processes. Metered
timestamp/receipt/hash calls proxy to middleware when ZAPPIER_UPSTREAM
is set. CS credits, sales per-customer pricing, and QuickBooks export
are separate repos plugged into zappier-edge admin.

packages/zappier-accounting-export/src/server.js

@@ -0,0 +1,42 @@
+#!/usr/bin/env node
+/** Accounting department: QuickBooks IIF + CSV from zappier-edge invoices. */
+import http from 'node:http';
+
+const PORT = Number(process.env.PORT || 3013);
+const EDGE = (process.env.ZAPPIER_ADMIN_URL || 'http://127.0.0.1:3000').replace(/\/$/, '');
+const KEY = process.env.ZAPPIER_ADMIN_KEY || 'admin-dev-key';
+
+async function edge(pathname) {
+  const r = await fetch(`${EDGE}${pathname}`, { headers: { 'x-admin-key': KEY } });
+  return r;
+}
+
+const server = http.createServer(async (req, res) => {
+  const url = new URL(req.url || '/', `http://127.0.0.1:${PORT}`);
+  const send = (code, type, body) => {
+    res.writeHead(code, { 'content-type': type });
+    res.end(body);
+  };
+  try {
+    if (req.method === 'GET' && url.pathname === '/health') {
+      return send(200, 'application/json', JSON.stringify({ ok: true, role: 'zappier-accounting-export' }));
+    }
+    const period = url.searchParams.get('period');
+    const q = period ? `?period=${encodeURIComponent(period)}` : '';
+    if (req.method === 'GET' && url.pathname === '/export/quickbooks.iif') {
+      const r = await edge(`/admin/api/exports/quickbooks.iif${q}`);
+      return send(r.status, 'text/plain', await r.text());
+    }
+    if (req.method === 'GET' && url.pathname === '/export/accounting.csv') {
+      const r = await edge(`/admin/api/exports/accounting.csv${q}`);
+      return send(r.status, 'text/csv', await r.text());
+    }
+    send(404, 'application/json', JSON.stringify({ error: 'not found' }));
+  } catch (err) {
+    send(502, 'application/json', JSON.stringify({ error: err.message }));
+  }
+});
+
+server.listen(PORT, '0.0.0.0', () => {
+  process.stdout.write(`zappier-accounting-export http://127.0.0.1:${PORT}/\n`);
+});