Per-PR ephemeral email inboxes for E2E tests in GitHub Actions

Your password-reset flow needs an inbox to test against. Your invitation flow too. Your email-verification gate too. The classic setup is a " [email protected] " alias on a shared mailbox, polling Gmail's API, hoping nothing else lands while the test runs. It is fragile, it leaks state across PRs, and your credentials live in CI. A managed agent account flips this. Each PR gets a fresh inbox, lives only for the duration of the test run, and tears itself down at the end. What this gives