Limit request sizes, answer 413, stop cleanly on SIGTERM

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UaC9HmtHMdRP8dAbN4wAKj

body.js

@@ -0,0 +1,11 @@
+'use strict';
+// Reads a request body as text, and refuses one that is too big, so a huge upload cannot use up the server's memory.
+function readBody(req, max = 2e6) {
+  return new Promise((ok, no) => {
+    const c = []; let n = 0, done = false;
+    req.on('data', d => { if (done) return; n += d.length; if (n > max) { done = true; c.length = 0; const e = new Error('That is too large'); e.status = 413; no(e); return; } c.push(d); });
+    req.on('end', () => { if (!done) ok(Buffer.concat(c).toString()); });
+    req.on('error', e => { if (!done) no(e); });
+  });
+}
+module.exports = { readBody };