suggestion: improve footer tabs

Please enhance the footer tabs. There is this limitation listed in the bottom tab bar:

> ⚠️ DISCLAIMER: ONLY Use tabs at the root level (The first view that shows up on launch). Any other usage may introduce unexpected behavior.

I found this to be true. However, forcing all apps to display a footer with tabs from the launch view if they ever want to use tabs is rather restrictive and generally very awkward for app design and UX.

One work-around I found to work is to transition from a view without footer to a view with a footer via a "replace" transition, so that the user cannot go "back" into the non-tabbed view. I found this to work reliably, though I am not sure if it's something the project can condone. If this is "safe" to do, it may be a somewhat acceptable work-around in general and would be good to have documented for others, making the framework more versatile.

I typically design my apps to have a footer when the user is logged in. Replacing the "top" view into and out of tabs works for me.

Start by reviewing the bottom tab bar behavior and the existing root-level limitation, then examine how the reported replace transition interacts with footer tabs. Determine whether non-root tab usage can be supported safely or whether the workaround should be documented. Done means the supported behavior and its limitations are clear to app developers.

Written by the indexing model from the issue text.