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-customer-service/src/server.js

@@ -0,0 +1,73 @@
+#!/usr/bin/env node
+/**
+ * Customer-service department API: goodwill credits, CS notes.
+ * Source of truth for balances remains zappier-edge admin.
+ */
+import http from 'node:http';
+import fs from 'node:fs';
+import path from 'node:path';
+
+const PORT = Number(process.env.PORT || 3011);
+const EDGE = (process.env.ZAPPIER_ADMIN_URL || 'http://127.0.0.1:3000').replace(/\/$/, '');
+const KEY = process.env.ZAPPIER_ADMIN_KEY || 'admin-dev-key';
+const STORE = process.env.CS_STORE || path.join(process.cwd(), 'data', 'credits.json');
+
+function load() {
+  try {
+    return JSON.parse(fs.readFileSync(STORE, 'utf8'));
+  } catch {
+    return { credits: [] };
+  }
+}
+function save(data) {
+  fs.mkdirSync(path.dirname(STORE), { recursive: true });
+  fs.writeFileSync(STORE, JSON.stringify(data, null, 2));
+}
+
+async function edge(pathname, { method = 'GET', body } = {}) {
+  const r = await fetch(`${EDGE}${pathname}`, {
+    method,
+    headers: { 'content-type': 'application/json', 'x-admin-key': KEY },
+    body: body ? JSON.stringify(body) : undefined,
+  });
+  const text = await r.text();
+  try {
+    return { status: r.status, body: JSON.parse(text) };
+  } catch {
+    return { status: r.status, body: text };
+  }
+}
+
+const server = http.createServer(async (req, res) => {
+  const url = new URL(req.url || '/', `http://127.0.0.1:${PORT}`);
+  const json = (code, obj) => {
+    res.writeHead(code, { 'content-type': 'application/json' });
+    res.end(JSON.stringify(obj));
+  };
+  try {
+    if (req.method === 'GET' && url.pathname === '/health') {
+      return json(200, { ok: true, role: 'zappier-customer-service' });
+    }
+    if (req.method === 'POST' && url.pathname === '/credits') {
+      const chunks = [];
+      for await (const c of req) chunks.push(c);
+      const payload = JSON.parse(Buffer.concat(chunks).toString('utf8') || '{}');
+      const forwarded = await edge('/admin/api/credits', { method: 'POST', body: payload });
+      const data = load();
+      data.credits.unshift({ ...payload, at: new Date().toISOString(), edge: forwarded.status });
+      save(data);
+      return json(forwarded.status, forwarded.body);
+    }
+    if (req.method === 'GET' && url.pathname === '/credits') {
+      const forwarded = await edge(`/admin/api/credits${url.search}`);
+      return json(forwarded.status, forwarded.body);
+    }
+    json(404, { error: 'not found' });
+  } catch (err) {
+    json(502, { error: err.message });
+  }
+});
+
+server.listen(PORT, '0.0.0.0', () => {
+  process.stdout.write(`zappier-customer-service http://127.0.0.1:${PORT}/\n`);
+});