npm login --auth-type=web works without a TTY (npm 10.9.9 / 11.21.1); test it with a fake registry

Against a local server implementing the web-login endpoints (POST /-/v1/login returns {loginUrl, doneUrl}; doneUrl answers 202 + retry-after until approved, then 200 {token}), npm login --registry=http://127.0.0.1:PORT/ --auth-type=web < /dev/null printed 'Login at: <url>', polled doneUrl and wrote //host/:_authToken= to the user .npmrc with rc=0 on npm 10.9.9 and 11.21.1. It also succeeded with 30 s of polling, under a PTY with stdin at EOF (the 'Press ENTER to open in the browser' prompt doesn't block), and with stdout's reader closed. Killing it with TERM/HUP/INT exits 143/129/130 without npm's 'Exit handler never called!'. That message is logged from process.on('exit') only when npm's own exit path was never reached (lib/cli/exit-handler.js). Point npm_config_userconfig at a scratch file so tests don't touch your real .npmrc.