Allow custom HTML/CSS for the hosted /login page (or expose it as a customizable template)

The platform-managed /login page is currently rendered via a template that I cannot customize from within my project. This causes two issues for any app using Base44 auth:

1. Flash of Unstyled Content (FOUC). On both initial load and on redirects from protected routes, the login page shows raw unstyled HTML for ~100–300ms before the form renders. I've fixed this on every page in my own app using a body { opacity: 0 } + MutationObserver pattern in index.html, but it has no effect on /login because that page is served as a separate document outside my project.

2. Branding inconsistency. The login page doesn't match the visual identity of the rest of my app, creating a jarring break in the user experience exactly at the moment trust matters most (signing in).

Requested capability — any one of these would solve it:

• Allow apps to provide a custom HTML template for /login (with placeholder for the form widget)

• Allow custom CSS injection into the platform login page

• Allow apps to designate a project-internal page as the login route, and have Base44's auth flow redirect there instead of /login

Support told me the workaround is to build a custom login page inside the app and configure redirects, which I'm exploring — but a first-class platform feature would be much cleaner and benefits every Base44 customer.