Sign an agent into a website using a `login` credential from the vault, in a browser reached over its RPC port. The password goes from the vault straight into the page and is never seen by the agent; a 2FA step is answered from a stored TOTP seed or by a card raised to the owner at the moment the site sends the code. A recipe on the credential drives multi-step and identity-provider forms. Use when a task needs an account and the browser is signed out; driving the browser otherwise is not this plugin's job.
