GitHub-style strict baseline

Inspired by: GitHub 2FA, Cloudflare dashboard, and other well-engineered modern 2FA pages that declare autocomplete="one-time-code".
Pattern: Single input with autocomplete="one-time-code", name="totp", maxlength="6", inputmode="numeric".
Hits: Strict TotpFieldNames list + the canonical autocomplete signal.
Expected with "Auto-fill 2FA codes on page load" off: Manual trigger fills (existing behavior).
Expected with the setting on: Page-load fills the code automatically. The cleanest baseline.

Two-Factor Authentication

Enter the 6-digit code from your authenticator app