A terminal
Install, sign in, publish. The key is written to a 0600 file; it is never printed, never passed as a flag and never reaches your shell history.
mkdir -p ~/.local/bin
curl -fsSL https://artifacthub.link/ah.mjs -o ~/.local/bin/ah
chmod +x ~/.local/bin/ah
ah login
On a machine with no browser, like a VPS, a container or an SSH session, ah login --device prints a URL and an eight-letter code you open on anything, a phone included. Needs Node 18 or newer, and nothing else.