The login page lived inside the authenticated AppShell, so the desktop
sidebar (with all nav items) and the mobile menu drawer were rendering
on the sign-in screen. AppShell now branches on pathname=/login and
renders a single centred header (cm + WhatsApp Bot) with no nav, plus
the form. Drops the redundant in-card title since the header carries
the brand.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>